Tweak G34, fix a declaration

Marlin/src/gcode/calibrate/G34_M422.cpp

   );
 #endif
 
-static xy_pos_t z_auto_align_pos[Z_STEPPER_COUNT] = Z_STEPPER_ALIGN_XY;
+//
+// G34 / M422 shared data
+//
+static xy_pos_t z_stepper_align_pos[] = Z_STEPPER_ALIGN_XY;
 
 #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
-  static xy_pos_t z_stepper_pos[] = Z_STEPPER_ALIGN_STEPPER_XY;
+  static xy_pos_t z_stepper_align_stepper_pos[] = Z_STEPPER_ALIGN_STEPPER_XY;
 #endif
 
-#define G34_PROBE_COUNT COUNT(z_auto_align_pos)
+#define G34_PROBE_COUNT COUNT(z_stepper_align_pos)
 
 inline void set_all_z_lock(const bool lock) {
   stepper.set_z_lock(lock);
     // iteration this will be re-calculated based on the actual bed position
     float z_probe = Z_BASIC_CLEARANCE + (G34_MAX_GRADE) * 0.01f * (
       #if ENABLED(Z_TRIPLE_STEPPER_DRIVERS)
-         SQRT(_MAX(HYPOT2(z_auto_align_pos[0].x - z_auto_align_pos[0].y, z_auto_align_pos[1].x - z_auto_align_pos[1].y),
-                   HYPOT2(z_auto_align_pos[1].x - z_auto_align_pos[1].y, z_auto_align_pos[2].x - z_auto_align_pos[2].y),
-                   HYPOT2(z_auto_align_pos[2].x - z_auto_align_pos[2].y, z_auto_align_pos[0].x - z_auto_align_pos[0].y)))
+         SQRT(_MAX(HYPOT2(z_stepper_align_pos[0].x - z_stepper_align_pos[0].y, z_stepper_align_pos[1].x - z_stepper_align_pos[1].y),
+                   HYPOT2(z_stepper_align_pos[1].x - z_stepper_align_pos[1].y, z_stepper_align_pos[2].x - z_stepper_align_pos[2].y),
+                   HYPOT2(z_stepper_align_pos[2].x - z_stepper_align_pos[2].y, z_stepper_align_pos[0].x - z_stepper_align_pos[0].y)))
       #else
-         HYPOT(z_auto_align_pos[0].x - z_auto_align_pos[0].y, z_auto_align_pos[1].x - z_auto_align_pos[1].y)
+         HYPOT(z_stepper_align_pos[0].x - z_stepper_align_pos[0].y, z_stepper_align_pos[1].x - z_stepper_align_pos[1].y)
       #endif
     );
 
         if (iteration == 0 || i > 0) do_blocking_move_to_z(z_probe);
 
         // Probe a Z height for each stepper.
-        const float z_probed_height = probe_at_point(z_auto_align_pos[iprobe], raise_after, 0, true);
+        const float z_probed_height = probe_at_point(z_stepper_align_pos[iprobe], raise_after, 0, true);
         if (isnan(z_probed_height)) {
           SERIAL_ECHOLNPGM("Probing failed.");
           err_break = true;
         incremental_LSF_reset(&lfd);
         for (uint8_t i = 0; i < G34_PROBE_COUNT; ++i) {
           SERIAL_ECHOLNPAIR("PROBEPT_", int(i + 1), ": ", z_measured[i]);
-          incremental_LSF(&lfd, z_auto_align_pos[i], z_measured[i]);
+          incremental_LSF(&lfd, z_stepper_align_pos[i], z_measured[i]);
         }
         finish_incremental_LSF(&lfd);
 
         z_measured_min = 100000.0f;
         for (uint8_t i = 0; i < Z_STEPPER_COUNT; ++i) {
-          z_measured[i] = -(lfd.A * z_stepper_pos[i].x + lfd.B * z_stepper_pos[i].y);
+          z_measured[i] = -(lfd.A * z_stepper_align_stepper_pos[i].x + lfd.B * z_stepper_align_stepper_pos[i].y);
           z_measured_min = _MIN(z_measured_min, z_measured[i]);
         }
 
 void GcodeSuite::M422() {
   if (!parser.seen_any()) {
     for (uint8_t i = 0; i < G34_PROBE_COUNT; ++i)
-      SERIAL_ECHOLNPAIR_P(PSTR("M422 S"), i + 1, SP_X_STR, z_auto_align_pos[i].x, SP_Y_STR, z_auto_align_pos[i].y);
+      SERIAL_ECHOLNPAIR_P(PSTR("M422 S"), i + 1, SP_X_STR, z_stepper_align_pos[i].x, SP_Y_STR, z_stepper_align_pos[i].y);
     #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
       for (uint8_t i = 0; i < Z_STEPPER_COUNT; ++i)
-        SERIAL_ECHOLNPAIR_P(PSTR("M422 W"), i + 1, SP_X_STR, z_stepper_pos[i].x, SP_Y_STR, z_stepper_pos[i].y);
+        SERIAL_ECHOLNPAIR_P(PSTR("M422 W"), i + 1, SP_X_STR, z_stepper_align_stepper_pos[i].x, SP_Y_STR, z_stepper_align_stepper_pos[i].y);
     #endif
     return;
   }
 
   xy_pos_t *pos_dest = (
     #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
-      !is_probe_point ? z_stepper_pos :
+      !is_probe_point ? z_stepper_align_stepper_pos :
     #endif
-    z_auto_align_pos
+    z_stepper_align_pos
   );
 
   if (!is_probe_point