drm/vc4: Correct condition for ignoring a plane to src rect =0, not <1.0

The logic for dropping a plane less than zero didn't account for the
possibility that a plane could be being upscaled with a src_rect with
width/height < 1 pixel, but not 0 subpixels.

Check for not 0 subpixels, not < 1, in both vc4 and vc6 paths.

Fixes: dac6168 ("drm/vc4: Drop planes that have 0 destination size")
Fixes: f73b18e ("drm/vc4: Drop planes that are completely off-screen")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

drivers/gpu/drm/vc4/vc4_plane.c

@@ -1129,7 +1129,8 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
 	width = vc4_state->src_w[0] >> 16;
 	height = vc4_state->src_h[0] >> 16;
 
-	if (!width || !height || !vc4_state->crtc_w || !vc4_state->crtc_h) {
+	if (!vc4_state->src_w[0] || !vc4_state->src_h[0] ||
+	    !vc4_state->crtc_w || !vc4_state->crtc_h) {
 		/* 0 source size probably means the plane is offscreen */
 		vc4_state->dlist_initialized = 1;
 		return 0;
@@ -1656,7 +1657,8 @@ static int vc6_plane_mode_set(struct drm_plane *plane,
 	width = vc4_state->src_w[0] >> 16;
 	height = vc4_state->src_h[0] >> 16;
 
-	if (!width || !height || !vc4_state->crtc_w || !vc4_state->crtc_h) {
+	if (!vc4_state->src_w[0] || !vc4_state->src_h[0] ||
+	    !vc4_state->crtc_w || !vc4_state->crtc_h) {
 		/* 0 source size probably means the plane is offscreen.
 		 * 0 destination size is a redundant plane.
 		 */