Let's migrate it to use runtime PM and remove the system
PM callback from this driver. With this patch, it could
handle system PM properly and could also use runtime PM
if we enable it.
Signed-off-by: NShawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>