drm/i915/display: Indexed 8bit format does not support async flip

Async flip is not supported with Indexed 8 bit format as it depends on
LUT and can't be updated atomically.

Note: This may change the alignment for C8 framebuffers on some
platforms.

Signed-off-by: Arun R Murthy <[e-mail]>
Reviewed-by: Ville Syrjälä <[e-mail]>
Signed-off-by: Suraj Kandpal <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/i915/display/intel_atomic_plane.c

···
 bool intel_plane_can_async_flip(struct intel_plane *plane, u32 format,
 				u64 modifier)
 {
-	if (intel_format_info_is_yuv_semiplanar(drm_format_info(format), modifier))
+	if (intel_format_info_is_yuv_semiplanar(drm_format_info(format), modifier) ||
+	    format == DRM_FORMAT_C8)
 		return false;
 
 	return plane->can_async_flip && plane->can_async_flip(modifier);