drm/simplefb: Drop [XA]RGB2101010 cross-conversion

Assuming Macs are the only platforms using this so far, the DTs have
always claimed XRGB2101010, so only the A->X path is relevant. Testing
suggests nothing depends on this. Let's drop it and see if anyone
complains.

Signed-off-by: Hector Martin <marcan@marcan.st>

drivers/gpu/drm/tiny/simpledrm.c

@@ -485,18 +485,6 @@ static const uint32_t simpledrm_primary_plane_formats_xrgb8888[] = {
 	//DRM_FORMAT_ARGB1555,
 };
 
-/*
- * Supported conversions to [AX]RGB2101010:
- *   A/X variants (no-op)
- *   from [AX]RGB8888
- */
-static const uint32_t simpledrm_primary_plane_formats_xrgb2101010[] = {
-	DRM_FORMAT_XRGB2101010,
-	DRM_FORMAT_ARGB2101010,
-	DRM_FORMAT_XRGB8888,
-	DRM_FORMAT_ARGB8888,
-};
-
 static const uint64_t simpledrm_primary_plane_format_modifiers[] = {
 	DRM_FORMAT_MOD_LINEAR,
 	DRM_FORMAT_MOD_INVALID
@@ -823,6 +811,8 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 	switch (format->format) {
 	case DRM_FORMAT_RGB565:
 	case DRM_FORMAT_RGB888:
+	case DRM_FORMAT_XRGB2101010:
+	case DRM_FORMAT_ARGB2101010:
 		conv_formats = simpledrm_primary_plane_formats_base;
 		conv_nformats = ARRAY_SIZE(simpledrm_primary_plane_formats_base);
 		break;
@@ -831,11 +821,6 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 		conv_formats = simpledrm_primary_plane_formats_xrgb8888;
 		conv_nformats = ARRAY_SIZE(simpledrm_primary_plane_formats_xrgb8888);
 		break;
-	case DRM_FORMAT_XRGB2101010:
-	case DRM_FORMAT_ARGB2101010:
-		conv_formats = simpledrm_primary_plane_formats_xrgb2101010;
-		conv_nformats = ARRAY_SIZE(simpledrm_primary_plane_formats_xrgb2101010);
-		break;
 	default:
 		conv_formats = NULL;
 		conv_nformats = 0;