[camera] Adding 'no-error' entry to camera_error

The camera_error_t does not have a 'no-error'
entry, which makes it difficut to check and
set explicitly.  This should have no effect
on existing code, since 0 was already the
implicit 'no-error' value.

Change-Id: Ie3ec85c32ff8cabe56b0561c8480554bd1b4ce51
diff --git a/system/public/zircon/device/camera.h b/system/public/zircon/device/camera.h
index 1c0828b..b586244 100644
--- a/system/public/zircon/device/camera.h
+++ b/system/public/zircon/device/camera.h
@@ -193,6 +193,7 @@
 } camera_vb_cmd_frame_release_resp_t;
 
 typedef enum camera_error {
+    CAMERA_ERROR_NONE = 0x0,
     // An error occurred during the production of a frame.
     // No data will be available in the data buffer corresponding to this
     // notification.