iwlwifi: mvm: set status before calling iwl_mvm_send_cmd_status()

We always must set the status to what we consider success before
calling iwl_mvm_send_cmd_status() (also iwl_mvm_send_cmd_pdu_status()
which calls it).  Fix a few places where initialization is missing.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>