Remove 'split.transport.protocol=serial_usart' (#23668)

data/schemas/keyboard.jsonschema

@@ -805,7 +805,7 @@
                     "properties": {
                         "protocol": {
                             "type": "string",
-                            "enum": ["custom", "i2c", "serial", "serial_usart"]
+                            "enum": ["custom", "i2c", "serial"]
                         },
                         "sync": {
                             "type": "object",

docs/reference_info_json.md

@@ -739,7 +739,7 @@ Configures the [Split Keyboard](feature_split_keyboard.md) feature.
         * Default: `1`
     * `transport`
         * `protocol`
-            * The split transport protocol to use. Must be one of `custom`, `i2c`, `serial`, `serial_usart`.
+            * The split transport protocol to use. Must be one of `custom`, `i2c`, `serial`.
         * `sync`
             * `activity`
                 * Mirror the activity timestamps to the secondary half.

keyboards/era/sirind/tomak/keyboard.json

@@ -183,7 +183,6 @@
             }
         },
         "transport": {
-            "protocol": "serial_usart",
             "sync": {
                 "indicators": true,
                 "layer_state": true,

keyboards/keychron/q11/info.json

@@ -54,7 +54,6 @@
             }
         },
         "transport": {
-            "protocol": "serial_usart",
             "sync" :{
                 "matrix_state": true
             }