mt76: mt76x2: move mt76x02_mac_reset_counters in mt76x02_mac_start

Move mt76x02_mac_reset_counters in mt76x02_mac_start and get rid of
mt76x2_mac_start since it is just a wrapper for mt76x02_mac_start

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>