SoC: s6 : support pwm driver [2/2]

PD#SWPL-156469

Problem:
there is no pwm driver

Solution:
support it

Verify:
s6 pxp

Change-Id: I66e07a651d5fdc8c25e18495948aca5a7c5e9ad4
Signed-off-by: Junyi Zhao <junyi.zhao@amlogic.com>
1 file changed