If the PWM pinctrl uses default state, the iomux setting will
be done at probe, the PWM may not be enabled at this moment.
It will make PWM into an intermediate state, destroy the default
hardware state, the PWM is not ready for work yet. So it is better
for doing PWM pinctrl setting after PWM enabled.
Change-Id: Iea34a7baf6a4d7df0c631f7f4fdab5b9d61bbd5f
Signed-off-by: David Wu <david.wu@rock-chips.com>