mt76: mt7921: Don't alter Rx path classifier

Keep Rx path classifier the mt7921 firmware prefers to allow frames pass
through MCU.

Fixes: 5c14a5f9 ("mt76: mt7921: introduce mt7921e support")
Reviewed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>