[][Fix mt7986 pwm driver broken by mt7981 patch]

[Description]
Fix mt7986 pwm driver broken by mt7981 patch.

We added mt7981 pwm support by splitting pwm regs into V1 and V2,
and marked mt7981 and mt7986 regs as V2, but actually mt7986 pwm
hardware is using regs V1.

[Release-log]
N/A

Change-Id: If54394d7a51aa39968a8bb2fa9b8019141d9dc4e
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6024629
1 file changed