Migrate half-duplex `SERIAL_USART_TX_PIN` to DD (#24143)

keyboards/chew/config.h

@@ -8,4 +8,3 @@
 #define RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT 200U // In ms in which the double tap can occur
 
 #define EE_HANDS
-#define SERIAL_USART_TX_PIN GP11

keyboards/chew/keyboard.json

@@ -33,7 +33,8 @@
             }
         },
         "serial": {
-            "driver": "vendor"
+            "driver": "vendor",
+            "pin": "GP11"
         },
         "transport": {
             "watchdog": true

keyboards/keychron/q11/config.h

@@ -29,9 +29,6 @@
 #define SNLED27351_CURRENT_TUNE \
     { 0x80, 0xFF, 0xFF, 0x80, 0xFF, 0xFF, 0x80, 0xFF, 0xFF, 0x80, 0xFF, 0xFF } // 300mA
 
-/* Split Keyboard specific options. */
-#define SERIAL_USART_TX_PIN A9 // USART TX pin
-
 /* Encoder Configuration */
 #define ENCODER_DEFAULT_POS 0x3
 

keyboards/keychron/q11/info.json

@@ -54,7 +54,8 @@
             }
         },
         "serial": {
-            "driver": "usart"
+            "driver": "usart",
+            "pin": "A9"
         },
         "transport": {
             "sync" :{

keyboards/mlego/m60_split/rev1/config.h

@@ -15,5 +15,4 @@
  */
 #pragma once
 
-#define SERIAL_USART_TX_PIN B6
 #define SERIAL_USART_SPEED 921600

keyboards/mlego/m60_split/rev1/keyboard.json

@@ -73,7 +73,8 @@
             }
         },
         "serial": {
-            "driver": "usart"
+            "driver": "usart",
+            "pin": "B6"
         },
         "transport": {
             "sync": {

keyboards/mlego/m60_split/rev2/config.h

@@ -15,8 +15,6 @@
  */
 #pragma once
 
-#define SERIAL_USART_TX_PIN B6
-
 #define SERIAL_USART_SPEED 921600
 
 #define RGBLIGHT_LAYERS

keyboards/mlego/m60_split/rev2/keyboard.json

@@ -66,7 +66,8 @@
             }
         },
         "serial": {
-            "driver": "usart"
+            "driver": "usart",
+            "pin": "B6"
         },
         "transport": {
             "sync": {

keyboards/pica40/rev2/config.h

@@ -3,8 +3,6 @@
 
 #pragma once
 
-#define SERIAL_USART_TX_PIN GP0
-
 #define RP2040_BOOTLOADER_DOUBLE_TAP_RESET
 #define RP2040_BOOTLOADER_DOUBLE_TAP_RESET_LED GP17
 #define RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT 500U

keyboards/pica40/rev2/keyboard.json

@@ -42,7 +42,8 @@
             }
         },
         "serial": {
-            "driver": "vendor"
+            "driver": "vendor",
+            "pin": "GP0"
         }
     },
     "encoder": {