fix: Remove unused getRHSMConfigOption() function

* This function was used only in GuessAPIURL() and it was removed
  in previous commit: f7e8ffa

rhsm.go

@@ -394,24 +394,6 @@ func configureRHSM(serverURL string) error {
 	return nil
 }
 
-func getRHSMConfigOption(name string, val interface{}) error {
-	conn, err := dbus.SystemBus()
-	if err != nil {
-		return fmt.Errorf("cannot connect to system D-Bus: %w", err)
-	}
-	locale := getLocale()
-	obj := conn.Object("com.redhat.RHSM1", "/com/redhat/RHSM1/Config")
-	if err := obj.Call(
-		"com.redhat.RHSM1.Config.Get",
-		dbus.Flags(0),
-		name,
-		locale).Store(val); err != nil {
-		return unpackRHSMError(err)
-	}
-
-	return nil
-}
-
 // registerRHSM tries to register system against Red Hat Subscription Management server (candlepin server)
 func registerRHSM(ctx *cli.Context) (string, error) {
 	uuid, err := getConsumerUUID()