iwlwifi: trans: add suspend/resume ops

Add suspend/resume trans ops that will be called from
mac80211's suspend/resume ops.

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>