[][kernel][common][pwm][Add pwm-gpio driver to Kconfig and Makefile]

[Description]
Add pwm-gpio driver to Kconfig and Makefile.

[Release-log]
N/A

Change-Id: Iee3897ea7890103012b17a82422eeb156992a50d
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8471748
1 file changed