staging: brcm80211: enable driver counter functionality

The 802.11 core in the chipsets provides counters that are now
used to provide counter values to mac80211 through get_stats
callback. Counters related to ampdu and wmm (aka. wme) are not
yet incorporated.

Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Brett Rudley <brudley@broadcom.com>
Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>