iwlwifi: mvm: Add support for Energy based scan (EBS)

This patch enables Energy Based Scan (EBS) - intended to detect energy
on 5 GHz band channels. Passive scan on this band takes up to 2.64 sec
assuming 110mSec per-channel * 24 channels. EBS is designed to detect
energy on channels with intensive Wifi activity as well as those where
only beacons are transmitted. EBS completes sampling all channels within
shortest beacon frame transmission time. Total EBS duration is about 100
msec (typical beacon interval).
Detecting Wifi activity on 5 GHz band channels can significantly reduce
scan duration thus saving time and power. EBS failure reported by FW
disables EBS for current connection. It is re-enabled upon new
connection attempt on any WLAN interface.

Signed-off-by: Haim Dreyfuss <haim.dreyfuss@intel.com>
Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>