engine: resources: Remove named return params

Named return params aren't a favourite feature of mine, and they're
rarely used in the resource writing. They keep popping up because I once
used them and we've been copying and pasting code ever since. Get rid of
them all to help prevent the unnecessary spread.

engine/resources/svc.go

@@ -229,12 +229,13 @@ func (obj *SvcRes) Watch() error {
 
 // CheckApply checks the resource state and applies the resource if the bool
 // input is true. It returns error info and if the state check passed or not.
-func (obj *SvcRes) CheckApply(apply bool) (checkOK bool, err error) {
+func (obj *SvcRes) CheckApply(apply bool) (bool, error) {
 	if !systemdUtil.IsRunningSystemd() {
 		return false, fmt.Errorf("systemd is not running")
 	}
 
 	var conn *systemd.Conn
+	var err error
 	if obj.Session {
 		conn, err = systemd.NewUserConnection() // user session
 	} else {