Allow override of RAMPS CS Pins (#9472)

Marlin/src/pins/pins_RAMPS.h

 #define X_STEP_PIN         54
 #define X_DIR_PIN          55
 #define X_ENABLE_PIN       38
-#define X_CS_PIN           53
+#ifndef X_CS_PIN
+  #define X_CS_PIN         53
+#endif
 
 #define Y_STEP_PIN         60
 #define Y_DIR_PIN          61
 #define Y_ENABLE_PIN       56
-#define Y_CS_PIN           49
+#ifndef Y_CS_PIN
+  #define Y_CS_PIN         49
+#endif
 
 #define Z_STEP_PIN         46
 #define Z_DIR_PIN          48
 #define Z_ENABLE_PIN       62
-#define Z_CS_PIN           40
+#ifndef Z_CS_PIN
+  #define Z_CS_PIN         40
+#endif
 
 #define E0_STEP_PIN        26
 #define E0_DIR_PIN         28
 #define E0_ENABLE_PIN      24
-#define E0_CS_PIN          42
+#ifndef E0_CS_PIN
+  #define E0_CS_PIN        42
+#endif
 
 #define E1_STEP_PIN        36
 #define E1_DIR_PIN         34
 #define E1_ENABLE_PIN      30
-#define E1_CS_PIN          44
+#ifndef E1_CS_PIN
+  #define E1_CS_PIN        44
+#endif
+
+/**
+ * Default pins for TMC software SPI
+ */
+#if ENABLED(TMC_USE_SW_SPI)
+  #ifndef TMC_SW_MOSI
+    #define TMC_SW_MOSI    66
+  #endif
+  #ifndef TMC_SW_MISO
+    #define TMC_SW_MISO    44
+  #endif
+  #ifndef TMC_SW_SCK
+    #define TMC_SW_SCK     64
+  #endif
+#endif
 
 #if ENABLED(HAVE_TMC2208)
-  /*
+  /**
    * TMC2208 stepper drivers
    *
    * Hardware serial communication ports.
   //#define E1_HARDWARE_SERIAL Serial1
   //#define E2_HARDWARE_SERIAL Serial1
   //#define E3_HARDWARE_SERIAL Serial1
-  //#define E3_HARDWARE_SERIAL Serial1
+  //#define E4_HARDWARE_SERIAL Serial1
 
-  /*
+  /**
    * Software serial
    */