wifi: mt76: mt7996: add implicit beamforming support for mt7992

The configuration of mt7992 iBF has some differences to mt7996, rework
related code to make it work.
Also, most of our chipsets support iBF only on HT and VHT mode, except
mt7992 variant that has 5T on 5GHz band also supports iBF on HE and EHT
mode.

Co-developed-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Howard Hsu <howard-yh.hsu@mediatek.com>
Link: https://patch.msgid.link/20250114101026.3587702-9-shayne.chen@mediatek.com


Signed-off-by: Felix Fietkau <nbd@nbd.name>