drm/sun4i: tv: Remove unused mode_valid

The mode_valid implementation is pretty much a nop, let's remove it.
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220728-rpi-analog-tv-properties-v2-34-459522d653a7@cerno.tech

drivers/gpu/drm/sun4i/sun4i_tv.c

@@ -497,16 +497,8 @@ static int sun4i_tv_comp_get_modes(struct drm_connector *connector)
 	return i;
 }
 
-static int sun4i_tv_comp_mode_valid(struct drm_connector *connector,
-				    struct drm_display_mode *mode)
-{
-	/* TODO */
-	return MODE_OK;
-}
-
 static const struct drm_connector_helper_funcs sun4i_tv_comp_connector_helper_funcs = {
 	.get_modes	= sun4i_tv_comp_get_modes,
-	.mode_valid	= sun4i_tv_comp_mode_valid,
 };
 
 static void