Fix some lint errors in pkg/proxy

pkg/proxy/util/endpoints.go

@@ -39,12 +39,12 @@ func IPPart(s string) string {
 		return ""
 	}
 	// Check if host string is a valid IP address
-	if ip := net.ParseIP(host); ip != nil {
-		return ip.String()
-	} else {
+	ip := net.ParseIP(host)
+	if ip == nil {
 		klog.Errorf("invalid IP part '%s'", host)
+		return ""
 	}
-	return ""
+	return ip.String()
 }
 
 // PortPart returns just the port part of an endpoint string.