ath9k: Fix channelFlags for 2GHZ

CHANNEL_G has to be set for 2GHZ channels since
IS_CHAN_G() checks for this in channelFlags and not in
chanmode. To make things messier, ath9k_hw_process_ini()
checks for CHANNEL_G in chanmode and not in channelFlags.
The supreme, brain-searing fix is to set the
flag in both cases.

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