staging: brcm80211: remove checks for ANTSEL related compiler definitions

The source module antsel is always included in the current driver so
any checks for it being compiled in are redundant and have been removed.

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