drm: Don't return ERESTARTSYS to user-space.

That return code is for in-kernel use only.
Use EINTR instead.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>

drivers/gpu/drm/drm_lock.c

@@ -93,7 +93,7 @@ int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
 		/* Contention */
 		schedule();
 		if (signal_pending(current)) {
-			ret = -ERESTARTSYS;
+			ret = -EINTR;
 			break;
 		}
 	}