mt76: move mt76x02_set_irq_mask in mt76x02_mmio.c

Move mt76x02_set_irq_mask, mt76x02_irq_enable and mt76x02_irq_disable
in mt76x02-lib module in order to be reused by mt76x0 driver.
Moreover move irq_lock and irqmask in mt76_mmio data structure

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