gl-renderer: Add support for DRM_FORMAT_YUV444 buffers

This uses the existing infrastructure for dealing with planar YUV buffers and only adds the
relevant yuv_format_descriptor to the table.
Reviewed-by: Emmanuel Gil Peyrot <emmanuel.peyrot@collabora.com>

libweston/gl-renderer.c

@@ -1599,6 +1599,27 @@ struct yuv_format_descriptor yuv_formats[] = {
 			.format = DRM_FORMAT_R8,
 			.plane_index = 2
 		}}
+	}, {
+		.format = DRM_FORMAT_YUV444,
+		.input_planes = 3,
+		.output_planes = 3,
+		.texture_type = EGL_TEXTURE_Y_U_V_WL,
+		{{
+			.width_divisor = 1,
+			.height_divisor = 1,
+			.format = DRM_FORMAT_R8,
+			.plane_index = 0
+		}, {
+			.width_divisor = 1,
+			.height_divisor = 1,
+			.format = DRM_FORMAT_R8,
+			.plane_index = 1
+		}, {
+			.width_divisor = 1,
+			.height_divisor = 1,
+			.format = DRM_FORMAT_R8,
+			.plane_index = 2
+		}}
 	}
 };