ath9k: update kconfig to indicate support for AR9002 family

ath9k supports the AR9002 family of chipsets. This includes
the AR9285 and the miniPCI AR9223 and AR9220 (which themselves
have AR9280+AR5133).

We now refer people to the wiki page as it seems this is not
as popular as we would have hoped.

Reported-by: JD <jd1008@gmail.com>
Cc: Dakota Lee <Dakota.Lee@Atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>