ath9k_htc: Add PID/VID for a Ubiquiti WiFiStation

Roger says, Ubiquiti produce 2 versions of their WiFiStation USB adapter.  One
has an internal antenna, the other has an external antenna and
name suffix EXT.  They have separate USB ids and in distribution
openSUSE 12.2 (kernel 3.4.6), file /usr/share/usb.ids shows:

  0cf3  Atheros Communications, Inc.
       ...
       b002  Ubiquiti WiFiStation 802.11n [Atheros AR9271]
       b003  Ubiquiti WiFiStationEXT 802.11n [Atheros AR9271]

Add b002 Ubiquiti WiFiStation in the PID/VID list.

Reported-by: Roger Price <ath9k@rogerprice.org>
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>