mt76x0: eeprom: introduce mt76x0_tssi_enabled routine

Add mt76x0_tssi_enabled in order to check if tssi compensation
is enabled since mt76x0 condition differs from mt76x2 one.
Moreover move back mt76x02_temp_tx_alc_enabled and mt76x02_tssi_enabled
routines in mt76x2/eeprom.h since they are mt76x2 specific

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