ath9k: Update high power gain table for AR9300

Now that the Buffalo-specific initvals have been
moved to a separate array, update the default high
power TX gain table for all AR9300 v2.2 devices.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>