Backward compatible with old xApp descriptor

Change-Id: I390425c5e05b17f039e4bce5f99a02f788041ba2
Signed-off-by: Mohamed Abukar <abukar.mohamed@nokia.com>
diff --git a/pkg/xapp/db.go b/pkg/xapp/db.go
index a7302cd..e422cfd 100755
--- a/pkg/xapp/db.go
+++ b/pkg/xapp/db.go
@@ -73,6 +73,9 @@
 
 // NewSDLClient returns a new SDLClient.
 func NewSDLClient(ns string) *SDLClient {
+	if ns == "" {
+		ns = "sdl"
+	}
 	return &SDLClient{
 		db:    sdl.NewSdlInstance(ns, sdl.NewDatabase()),
 		stat:  Metric.RegisterCounterGroup(SDLCounterOpts, "SDL"),