[][mac80211][wifi6][mt76][rework mmio access flow]

[Description]
Refactor mmio access flow to avoid race condition when access registers.

[Release-log]
N/A

Change-Id: I4c796ed226cbf38f11dbeca61b0eeaca6969db37
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7883764
1 file changed