Add mt76x02_get_rx_gain and mt76x02_get_lna_gain utility routines
for rx gain parsing. mt76x02_get_rx_gain and mt76x02_get_lna_gain
will be reused for eeprom parsing in mt76x0 driver
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>