drm/cirrus: Remove format test from cirrus_fb_create()

The DRM core implements a format check when setting a framebuffer
for a plane. [1] Remove the unnecessary test from cirrus_fb_create().
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Link: https://elixir.bootlin.com/linux/v6.1/source/drivers/gpu/drm/drm_atomic.c#L629 # [1]
Link: https://patchwork.freedesktop.org/patch/msgid/20230215161517.5113-12-tzimmermann@suse.de

drivers/gpu/drm/tiny/cirrus.c

@@ -559,10 +559,6 @@ static struct drm_framebuffer*
 cirrus_fb_create(struct drm_device *dev, struct drm_file *file_priv,
 		 const struct drm_mode_fb_cmd2 *mode_cmd)
 {
-	if (mode_cmd->pixel_format != DRM_FORMAT_RGB565 &&
-	    mode_cmd->pixel_format != DRM_FORMAT_RGB888 &&
-	    mode_cmd->pixel_format != DRM_FORMAT_XRGB8888)
-		return ERR_PTR(-EINVAL);
 	if (cirrus_check_size(mode_cmd->width, mode_cmd->height, NULL) < 0)
 		return ERR_PTR(-EINVAL);
 	return drm_gem_fb_create_with_dirty(dev, file_priv, mode_cmd);