profile: Use btd_service for connect/disconnect

profile: Use btd_service for connect/disconnect

Change the btd_profile connect/disconnect callbacks to receive a
btd_service pointer. This should make it possible to handle multiple
instances of the same profile in a specific device.

The patch strongly influences how the profiles should interact with the
core. The state transitions, previously reported using the device.h API
(device_profile_connected() and device_profile_disconnected()), have
now been replaced by the btd_service API.

The transitions will then be propagated to device.c by means of the
conventional state-changed callback mechanism.