wifi: mt76: mt7996: prevent uninit return in mt7996_mac_sta_add_links

[Markus Elfring]

>> I suggest to avoid such repeated error code assignments.
>> Can an additional label be applied instead for this purpose?
>
> Please stop your "suggestions" on this list. None have really been
> helpful.
It seems that you care less then for the avoidance of duplicate source code
also for affected error/exception handling.

Regards,
Markus