[][mt7981: update spi clk in spi node]

[Description]
Fix spi clk in spi node for mt7981

[Release-log]
N/A

Change-Id: I0118ca02c839c6c0e8b52d901b820b1c65ec1bf0
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5335458
1 file changed