wifi: mt76: connac: enable critical packet mode support for mt7992

For mt7992 chipsets, critical packet mode should be properly configured
to let the HW SDO module correctly fill the AC queue in TX descriptors of
some higher priority packets such as ARP and ICMP.
Without this patch, HW queues may hang when running MU traffic.

Signed-off-by: Howard Hsu <howard-yh.hsu@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>