pinctrl: rockchip: Protect read-modify-write with the spinlock

There were a few instances where the rockchip pinctrl driver would do
read-modify-write with no spinlock.  Add a spinlock for these cases.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>