Broadcom's firmware requires every BSS to use MAC address with unique
last few bits. The amount of bits may depend on a particular firmware,
it was verified to be 2 for BCM43602 one.
If this condition won't be fulfilled firmware will reject such MAC:
brcmfmac: _brcmf_set_mac_address: Setting cur_etheraddr failed, -52

We don't want to simply set addr_mask as it would also disallow using
locally administrated bit. Instead let's build a list of addresses
manually enabling 0x2 bit for extra interfaces.
Signed-off-by: Rafa? Mi?ecki <zajec5@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>