ARM: SAMSUNG: Add suspend/resume support for S3C PWM driver

Reset period_ns and duty_ns values in suspend handler to avoid skip of
configuration if same values passed to pwm_config;
Restore invertion bit in resume handler.

Without this patch PWM works incorrectly after resume from suspend.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>