mt76: allow more channels, allowed in ETSI domain

While looking at the ETSI regulatory domain definitions
and a patch, which allows more channels for ath10k, I also
checked the channels allowed for mt76.

ETSI regulations would possibly allow to add channels 32, 68,
96, 144, 169 and 173. IEEE 802.11-2016 defines no operating class
for channels 32, 68 and 96. This leaves us channels 144, 169 and 173,
which are included in this patch.

I tested 169 and 173 with a mt76 based USB dongle (AVM AC 860) and they
worked fine. If I saw that right, these channels are also covered by
register definitions inside the driver.

Channel 144 should also work, but gets disabled by the kernel as of now.

Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
Signed-off-by: Felix Fietkau <nbd@nbd.name>