drm/etnaviv: short-circuit perfmon ioctls

The feature implementation isn't stable yet. Reject any attempt to use
the IOCTLs for now. This keeps most of the code in place, so we can stabilize
it in-tree, but keeps userspace from using the feature for now.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_drv.c

@@ -459,6 +459,9 @@ static int etnaviv_ioctl_pm_query_dom(struct drm_device *dev, void *data,
 	struct drm_etnaviv_pm_domain *args = data;
 	struct etnaviv_gpu *gpu;
 
+	/* reject as long as the feature isn't stable */
+	return -EINVAL;
+
 	if (args->pipe >= ETNA_MAX_PIPES)
 		return -EINVAL;
 
@@ -476,6 +479,9 @@ static int etnaviv_ioctl_pm_query_sig(struct drm_device *dev, void *data,
 	struct drm_etnaviv_pm_signal *args = data;
 	struct etnaviv_gpu *gpu;
 
+	/* reject as long as the feature isn't stable */
+	return -EINVAL;
+
 	if (args->pipe >= ETNA_MAX_PIPES)
 		return -EINVAL;