[PATCH] zd1211rw: Add UW2453 RF support

This patch adds support for another radio appearing in new devices: the
Ubec UW2453. It's more complicated than the other RF's we support, but
Ubec publish full tech specs so we're able to understand the vendor code
relatively well.

Now that we support UW2453, we also support Atheros' new USB chip: the
AR5007UG. From the little info we have, this appears to be just a
rebranded ZD1211B.

This RF code doesn't work very well -- lots more TX/RX errors than the
other RFs. However, the vendor driver doesn't do any better, so this is
all we can do for now.

[kune@deine-taler.de: bug fixes]
Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>