wifi: mt76: ignore key disable commands

This helps avoid cleartext leakage of already queued or powersave buffered
packets, when a reassoc triggers the key deletion.

Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230330091259.61378-1-nbd@nbd.name