staging: brcm80211: fix compiler warning in fullmac driver

Since 2.6.38-rc1 we are getting a compiler warning due to
changed API in net/cfg80211.h. This change fixes the warning
but driver will need to be modified later to handle the
additional parameters.

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