UPSTREAM: pwm: Use pwm_get/set_xxx() helpers where appropriate

UPSTREAM: pwm: Use pwm_get/set_xxx() helpers where appropriate

Use pwm_get/set_xxx() helpers instead of directly accessing the pwm->xxx
field. Doing that will ease adaptation of the PWM framework to support
atomic update.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
(cherry picked from commit 4b58896f72176b781816a9e14dcea5f755b19b5c)

Change-Id: Ic6bdaf2017bb292ef920604fba86805999cebf0c
Signed-off-by: Huang, Tao <huangtao@rock-chips.com>