mt76: fix tkip configuration for mt7615/7663 devices

Fix Tx-Rx MIC overwrite during TKIP hw key configuration

Fixes: 01cfc1b4

 ("mt76: mt7615: add BIP_CMAC_128 cipher support")
Tested-by: YN Chen <yn.chen@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>