Simply logic for connect and disconnect in HeadsetProfile

* connect: remove debug log of connect connected device. HeadsetService
  will check it and print related log.
* disconnect: remove connected device check logic. HeadsetService will
  check it.
* getConnectionStatus: remove connected device check logic.
  HeadsetService will check it.
* wrap if/else statement in curly brackets.

Bug: 111812003
Test: manual - connect/disconnect headset from Settings UI

Change-Id: I2c58362c236a26b38c8aa67eb3a3433d76f97e45