mwifiex: Add support for wowlan disconnect

This patch adds support for wowlan disconnect.

Signed-off-by: Maithili Hinge <maithili@marvell.com>
Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>