Bluetooth: Call API with empty string.

 - In case of redial null was sent from apps,
   due to NULL checks in JNI there was exception
   generated while calling stack API.Call stack
   API with empty string instead of null.

CRs-Fixed: 911108
Change-Id: Iedeb8a700a46145b250985b3f850f992dddcedc6
1 file changed