The framebuffer pixel format is already checked by the common code.
So there's no way an invalid format could reach the driver. So instead
of falling back to a default format, call BUG().
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>