UPSTREAM: pinctrl: rockchip: split out verification of mux settings

UPSTREAM: pinctrl: rockchip: split out verification of mux settings

We need to avoid calling regmap functions from irq handlers, so the next
commit is going to move the call to rockchip_set_mux() into an
irq_bus_sync_unlock handler.  But we can't return an error from there so
we still need to check the settings from rockchip_irq_set_type() and we
will use this new rockchip_verify_mux() function from there.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David Wu <david.wu@rock-chips.com>
(cherry picked from git.kernel.org thierry.reding/linux-pwm.git for-next
 commit 05709c3e88f5f0adb7889facbfd546c998f65d59)

Signed-off-by: David Wu <david.wu@rock-chips.com>
Change-Id: I421f9c2faf835ca821c574602d6b4a66cdde9769