The symbols is used for rockchip video codec driver,
which located driver/rockchip/video/mpp. When mpp is build
for module, it will be error.
Error message:
ERROR: "device_links_read_unlock"
[drivers/video/rockchip/mpp/rk_vcodec.ko] undefined!
ERROR: "device_links_read_lock" [drivers/video/rockchip/mpp/rk_vcodec.ko] undefined!
make[2]: *** [__modpost] Error 1
make[1]: *** [modules] Error 2
make: *** [kernel.img] Error 2
make: *** Deleting file `kernel.img'`
Change-Id: Ie412341c03ad71d257392a22249b62bedd0be58b
Signed-off-by: Ding Wei <leo.ding@rock-chips.com>