b43: treat LCNXN-PHY as extra N-PHY devices

LCNXN is simply a continuation of N, e.g. code handling LCNXN revs 0 and
1 is mostly the same as for N-PHY revs 7+.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>