iwlwifi: mvm: fix EBS on single scan

EBS error detection isn't supported by all FWs, so turn it on
only if the FW advertises such support.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>