iwlwifi: mvm: Enable power save on a single P2P client interface

Enable power save on P2P client interface only if it is the
only bound interface.
Avoid using uAPSD if P2P client is associated to GO that uses
opportunistic power save. This is due to current FW limitation.

Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>