mt76: add rd_rp and wr_rp to bus_ops/mcu_ops

Add callbacks for reading and writing reg pairs tables.

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