ath9k: wake hardware for interface IBSS/AP/Mesh removal

When we remove a IBSS/AP/Mesh interface we stop DMA
but to do this we should ensure hardware is on. Awaken
the device prior to these calls. This should ensure
DMA is stopped upon suspend and plain device removal.

Cc: stable@kernel.org
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>