RemoteDevices: Use String(val) to set a remote device alias

DeviceProperties::mAlias is of type String. Always construct a new
String from the byte array and use that.

Bug: 29363875
Test: Manual test with android LE scanning app.
Confirmed that FRIENDLY_NAME update would not throw exceptions.

Change-Id: I6648e4ca8f0907ea338cd2932bda72b630692427