wifi: mt76: fix 5 GHz connection regression on mt76x0/mt76x2

wifi: mt76: fix 5 GHz connection regression on mt76x0/mt76x2

Some users have reported being unable to connect to MT76x0 APs running mt76
after a commit enabling the VHT extneded NSS BW feature.
Fix this regression by ensuring that this feature only gets enabled on drivers
that support it

Cc: stable@vger.kernel.org
Fixes: d9fcfc1424aa ("mt76: enable the VHT extended NSS BW feature")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220907095228.82072-1-nbd@nbd.name