drm/v3d: fix copy_from_user() error codes

The copy_to/from_user() function returns the number of bytes remaining
to be copied, but we want to return -EFAULT on error.

Fixes: e4165ae8304e ("drm/v3d: add multiple syncobjs support")
Signed-off-by: Dan Carpenter <[e-mail]>
Reviewed-by: Melissa Wen <[e-mail]>
Signed-off-by: Melissa Wen <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/20211011123303.GA14314@kili

drivers/gpu/drm/v3d/v3d_gem.c

···
 			for (i = 0; i < se->in_sync_count; i++) {
 				struct drm_v3d_sem in;
 
-				ret = copy_from_user(&in, handle++, sizeof(in));
-				if (ret) {
+				if (copy_from_user(&in, handle++, sizeof(in))) {
+					ret = -EFAULT;
 					DRM_DEBUG("Failed to copy wait dep handle.\n");
 					goto fail_deps;
 				}
···
 	for (i = 0; i < count; i++) {
 		struct drm_v3d_sem out;
 
-		ret = copy_from_user(&out, post_deps++, sizeof(out));
-		if (ret) {
+		if (copy_from_user(&out, post_deps++, sizeof(out))) {
+			ret = -EFAULT;
 			DRM_DEBUG("Failed to copy post dep handles\n");
 			goto fail;
 		}
···
 	struct v3d_submit_ext *se = data;
 	int ret;
 
-	ret = copy_from_user(&multisync, ext, sizeof(multisync));
-	if (ret)
-		return ret;
+	if (copy_from_user(&multisync, ext, sizeof(multisync)))
+		return -EFAULT;
 
 	if (multisync.pad)
 		return -EINVAL;