iwlwifi: mvm: only release the trans ref if d0i3 is supported in fw

If d0i3 is not supported by the firmware (or if it's disabled via
module parameters) we shouldn't release the initial transport
reference, so that we won't enter runtime suspend.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>