net: rmnet_data: Add trace points for device force unassociation

Added trace points to debug processing time of rmnet_config_notify_cb.
Additionally, tracepoints were added for succesfull associate/unassociate
events. Needed to debug unusually slow cleanup.

New trace points are:
rmnet_unregister_cb_unhandled
rmnet_unregister_cb_entry
rmnet_unregister_cb_exit
rmnet_unregister_cb_clear_vnds
rmnet_unregister_cb_clear_lepcs
rmnet_associate
rmnet_unassociate

Change-Id: I0269435d9c7234ef21092ba13510fff106a1966f
Signed-off-by: Harout Hedeshian <harouth@codeaurora.org>