staging: brcm80211: remove devpath related nvram variable lookup

The lookup function used for the devpath related functions did
not provide a variable table so the lookup would always fail. As
this makes the functions pretty useless these have been removed.

Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>