ath9k_htc: Really fix packet injection

The chainmask value along with other configuration has to be set
on the target for packet injection. Fix this and also move the monitor
interface addition before the channel set segment to ensure that
the opmode is updated properly.

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