🩹 BTT Manta M8P V2.0 fixes (#27748)

The notorious curse of incorrect BTT pins rears its head once again!

Author: ellensp

Marlin/src/pins/stm32h7/pins_BTT_MANTA_M8P_V2_0.h

@@ -307,7 +307,6 @@
   //#define Y_HARDWARE_SERIAL  Serial1
   //#define Y2_HARDWARE_SERIAL Serial1
   //#define Z_HARDWARE_SERIAL  Serial1
-  //#define Z2_HARDWARE_SERIAL Serial1
   //#define E0_HARDWARE_SERIAL Serial1
   //#define E1_HARDWARE_SERIAL Serial1
   //#define E2_HARDWARE_SERIAL Serial1
@@ -317,11 +316,11 @@
   #define X_SERIAL_TX_PIN                   PC13
   #define Y_SERIAL_TX_PIN                   PE3
   #define Z_SERIAL_TX_PIN                   PB9
-  #define Z2_SERIAL_TX_PIN                  PB5
-  #define E0_SERIAL_TX_PIN                  PG14
-  #define E1_SERIAL_TX_PIN                  PG10
-  #define E2_SERIAL_TX_PIN                  PD5
-  #define E3_SERIAL_TX_PIN                  PC6
+  #define E0_SERIAL_TX_PIN                  PB5
+  #define E1_SERIAL_TX_PIN                  PG14
+  #define E2_SERIAL_TX_PIN                  PG10
+  #define E3_SERIAL_TX_PIN                  PD5
+  #define E4_SERIAL_TX_PIN                  PC6
 
   // Reduce baud rate to improve software serial reliability
   #ifndef TMC_BAUD_RATE