Move mt76x02_rate_power_val and mt76x2_sign_extend_optional utility
routines in mt76x02_eeprom.h in order to reuse them in mt76x0 eeprom
parsing
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>