UPSTREAM: pwm: sysfs: Get return value from pwm_apply_state()

UPSTREAM: pwm: sysfs: Get return value from pwm_apply_state()

This patch adds to check the return value from pwm_apply_state()
used in enable_store(). The error of enable_store() doesn't work
if the return value doesn't received.

Signed-off-by: Ryo Kodama <ryo.kodama.vz@renesas.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Fixes: 39100ceea79f ("pwm: Switch to the atomic API")
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
(cherry picked from commit fe5aa34d6eb9c4d34071845f70f3714b41c8a77d)

Change-Id: I550da28345bcee7a6aa8e1f9b5c43adae923ff2d
Signed-off-by: David Wu <david.wu@rock-chips.com>