[][kernel][mt7988][pwm][add longer pwm period support]

[Description]
Add longer pwm period support for mediatek PWM, this make customer
able to blink LED via PWM pins.

[Release-log]
N/A

Change-Id: I75f566240ce6f0d8d9729de998f07e2bcba378d4

Change-Id: I30a738d053bc875c6c6ff9cb415d2b3c37441d4a
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6705185
1 file changed