Move RGB_MATRIX_DRIVER to data driven (#20350)

keyboards/miller/gm862/info.json

@@ -8,6 +8,9 @@
         "pid": "0x0223",
         "device_version": "0.0.1"
     },
+    "rgb_matrix": {
+        "driver": "IS31FL3733"
+    },
     "matrix_pins": {
         "cols": ["B5", "B6", "C6", "C7", "F7", "F6", "B0", "B1", "B2", "B3", "B7", "D2", "D3", "D5"],
         "rows": ["F0", "F1", "F4", "F5", "B4"]

keyboards/miller/gm862/rules.mk

@@ -11,5 +11,4 @@ BACKLIGHT_ENABLE = no          # Enable keyboard backlight functionality
 RGBLIGHT_ENABLE = no           # Enable keyboard RGB underglow
 AUDIO_ENABLE = no              # Audio output
 RGB_MATRIX_ENABLE = yes        # Use RGB matrix
-RGB_MATRIX_DRIVER = IS31FL3733
 NO_USB_STARTUP_CHECK = no      # Disable initialization only when usb is plugged in