ath10k: enable beacon loss detection support for 10.4

Enable beacon loss detection support for 10.4 by handling
roam event. With this change QCA99X0 station is able to
detect beacon loss when the AP is powered off

Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>