mt76: mt7615: mt7622: fix ibss and meshpoint

commit 7f4b7920 ("mt76: mt7615: add ibss support") introduced IBSS
and commit f4ec7fdf ("mt76: mt7615: enable support for mesh")
meshpoint support.

Both used in the "get_omac_idx"-function:

	if (~mask & BIT(HW_BSSID_0))
		return HW_BSSID_0;

With commit d8d59f66 ("mt76: mt7615: support 16 interfaces") the
ibss and meshpoint mode should "prefer hw bssid slot 1-3". However,
with that change the ibss or meshpoint mode will not send any beacon on
the mt7622 wifi anymore. Devices were still able to exchange data but
only if a bssid already existed. Two mt7622 devices will never be able
to communicate.

This commits reverts the preferation of slot 1-3 for ibss and
meshpoint. Only NL80211_IFTYPE_STATION will still prefer slot 1-3.

Tested on Banana Pi R64.

Fixes: d8d59f66

 ("mt76: mt7615: support 16 interfaces")
Signed-off-by: Nick Hainke <vincent@systemli.org>
Acked-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211007225725.2615-1-vincent@systemli.org