Reduce redundancy in BLTOUCH conditionals

Marlin/Conditionals_LCD.h

     #define BLTOUCH_RESET    160
     #define _TEST_BLTOUCH(P) (READ(P##_PIN) != P##_ENDSTOP_INVERTING)
 
+    // Always disable probe pin inverting for BLTouch
+    #undef Z_MIN_PROBE_ENDSTOP_INVERTING
+    #define Z_MIN_PROBE_ENDSTOP_INVERTING false
+
     #if ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)
       #undef Z_MIN_ENDSTOP_INVERTING
       #define Z_MIN_ENDSTOP_INVERTING false
-      #undef Z_MIN_PROBE_ENDSTOP_INVERTING
-      #define Z_MIN_PROBE_ENDSTOP_INVERTING false
       #define TEST_BLTOUCH() _TEST_BLTOUCH(Z_MIN)
     #else
-      #undef Z_MIN_PROBE_ENDSTOP_INVERTING
-      #define Z_MIN_PROBE_ENDSTOP_INVERTING false
       #define TEST_BLTOUCH() _TEST_BLTOUCH(Z_MIN_PROBE)
     #endif
   #endif