drm/v3d: fix a missing check of pm_runtime_get_sync

pm_runtime_get_sync could fail and thus deserves a check.

The patch adds such a check and return its error code upstream
if it indeed failed.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190324231602.2436-1-kjlu@umn.eduReviewed-by: Mukesh Ojha <mojha@codeaurora.org>

drivers/gpu/drm/v3d/v3d_drv.c

@@ -102,6 +102,8 @@ static int v3d_get_param_ioctl(struct drm_device *dev, void *data,
 			return -EINVAL;
 
 		ret = pm_runtime_get_sync(v3d->dev);
+		if (ret < 0)
+			return ret;
 		if (args->param >= DRM_V3D_PARAM_V3D_CORE0_IDENT0 &&
 		    args->param <= DRM_V3D_PARAM_V3D_CORE0_IDENT2) {
 			args->value = V3D_CORE_READ(0, offset);