drm: Pretty print pixel format in drm_fb_get_bpp_depth() and format_check()

drm_fb_get_bpp_depth() likes to complain about unsupported pixel formats
but doesn't bother telling us what the format was. Also format_check()
just returns an error when it encouters an invalid format, leaving the
user scratching his head trying to figure out why addfb failed. Make
life a bit easier by using drm_get_format_name() in both places.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_crtc.c

@@ -2489,6 +2489,8 @@ static int format_check(const struct drm_mode_fb_cmd2 *r)
 	case DRM_FORMAT_YVU444:
 		return 0;
 	default:
+		DRM_DEBUG_KMS("invalid pixel format %s\n",
+			      drm_get_format_name(r->pixel_format));
 		return -EINVAL;
 	}
 }
@@ -3828,7 +3830,8 @@ void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
 		*bpp = 32;
 		break;
 	default:
-		DRM_DEBUG_KMS("unsupported pixel format\n");
+		DRM_DEBUG_KMS("unsupported pixel format %s\n",
+			      drm_get_format_name(format));
 		*depth = 0;
 		*bpp = 0;
 		break;