[PATCH] zd1211rw: Add AL2230S RF support

ZD1211 appears to be back in production: a number of new devices have
been appearing! Some of them are using new radios.

This patch adds support for the next generation AL2230 RF chip which has
been spotted in a few new devices.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>