wifi: mt76: mt7915: fix capabilities in non-AP mode

Capabilities in vif->bss_conf are only initialized in AP mode.
For other modes, they should be enabled by default, in order to avoid a
mismatch.

Fixes: 885f7af7 ("wifi: mt76: mt7915: remove mt7915_mcu_beacon_check_caps()")
Signed-off-by: Felix Fietkau <nbd@nbd.name>