wifi: mt76: mt7996: support writing MAC TXD for AddBA Request

Support writing MAC TXD for the AddBA Req. Without this commit, the
start sequence number in AddBA Req will be unexpected value for MT7996
and MT7992. This can result in certain stations (e.g., AX200) dropping
packets, leading to ping failures and degraded connectivity. Ensuring
the correct MAC TXD and TXP helps maintain reliable packet transmission
and prevents interoperability issues with affected stations.

Signed-off-by: Howard Hsu <howard-yh.hsu@mediatek.com>
Link: https://patch.msgid.link/20250909-mt7996-addba-txd-fix-v1-1-feec16f0c6f0@kernel.org


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