Staging: stlc45xx: convert config_interface to bss_info_changed, fixing a build error

See commit 2d0ddec5 (mac80211: unify config_interface and
bss_info_changed)

This fixes a build error.

Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>