mt76: unify rxwi parsing between mt76x2 and mt76x0 drivers

Unify rxwi parsing between mt76x2 and mt76x0. Remove the following
routines:
- mt76x0_phy_get_rssi
- mt76x0_queue_rx_skb
- mt76x0_mac_process_rx
Moreover remove mt76x2/common.c and mt76x0/mac.h since are empty files
Enable CCMP PN sw validation

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>