brcmfmac: support monitor frames with the hardware/ucode header

So far there were two monitor frame formats:
1) 802.11 frames (with frame (sub)type & all addresses)
2) 802.11 frames with the radiotap header

Testing the latest FullMAC firmwares for 4366b1/4366c0 resulted in
discovering a new format being used. It seems (almost?) identical to the
one known from ucode used in SoftMAC devices which is most likely the
same codebase anyway.

While new firmwares will /announce/ radiotap header support using the
"rtap" fw capability string it seems no string was added for the new
ucode header format.

All above means that:
1) We need new format support when dealing with a received frame
2) A new feature bit & mapping quirks have to be added manually

As for now only an empty radiotap is being created. Adding support for
extracting some info (band, channel, signal, etc.) is planned for the
future.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>