[] [Add spi runtime PM support]

[Description]
Add ahb clk and enable runtime pm

[Release-log]
N/A

Change-Id: I0529f6e829f5fc4c5880508971c97b9434820340
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4747620
1 file changed