iwlwifi: mvm: Fix a few EBS error handling bugs

Last EBS status wasn't set to success in the initialization, which
caused the first scan to be without EBS. Fix that.

When EBS is not enabled by the driver, the FW still sends ebs_status success,
which can override EBS failure state. Consider only EBS failures, to avoid
such override. Last_ebs_success is set back to true upon disconnection.

Last_ebs_success wasn't set in umac scan abort flow, fix that too.

Signed-off-by: Haim Dreyfuss <haim.dreyfuss@intel.com>
Signed-off-by: David Spinadel <david.spinadel@intel.com>
Reviewed-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>