GATT: New callback API for notification state change
Make new callback api for notification enable/disable which
provides additional functionality of reporting client address
on notification state change.
This patchset should be merged with the following bluez and
bluetooth-frwk's patchset in order to match API and avoid crash:
bluez Change-Id:I81a0994f2299e988f8ef6428537647c899700fda
bluetooth-frwk Change-Id: Ib54ba54c318692b4ee0eaef9b2310c60dadeb661
Change-Id: Ic4868234a4fc682f9bff2c66ac1aee2683f3d6c6
Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>