Phone: Fix class cast exception in Phone app.

While handling CALL_PRIVILEGED intent with scheme type
"content", PhoneApp storing Uri type object in userdata
field of Connection object, but while retrieving it type
casting to the CallerInfoToken class and due to that
class cast Exception is observed in PhoneApp.

To fix it, added check to properly type cast the userdata
field of Connection object to Uri type class.

Change-Id: I4094b5c6025202e808b050973cb202c0bf2e61e7