ath9k: advertise supported WoW flags to upper layer

currently the code supports WoW triggers due to
*magic packet
*user defined patterns
*deauth and disassoc patterns
*disconnect - beacon miss, last beacon received timeout,
no ack for keeep alive frames.

Cc: Senthil Balasubramanian <senthilb@qca.qualcomm.com>
Cc: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Cc: vadivel@qca.qualcomm.com
Signed-off-by: Luis R. Rodriguez <mcgrof@qca.qualcomm.com>
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>