staging: brcm80211: rename pointer conversion macros in wl_cfg80211.h

The data structures in fullmac driver references are made easier by
using provided macros in wl_cfg80211.h. The abbreviation 'wl' in these
macros has been replaced by cfg or the macro has been removed if used
only once.

Signed-off-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>