Update TMC section with SW SPI pins (#9554)

Marlin/src/pins/pins_RAMPS.h

   //#define X2_HARDWARE_SERIAL Serial1
   //#define Y_HARDWARE_SERIAL  Serial1
   //#define Y2_HARDWARE_SERIAL Serial1
-  #define Z_HARDWARE_SERIAL  Serial3
-  #define Z2_HARDWARE_SERIAL Serial1
+  //#define Z_HARDWARE_SERIAL  Serial3
+  //#define Z2_HARDWARE_SERIAL Serial1
   //#define E0_HARDWARE_SERIAL Serial1
   //#define E1_HARDWARE_SERIAL Serial1
   //#define E2_HARDWARE_SERIAL Serial1