Bluetooth: GATT: Indicate service changes when reconnecting

If peer has previously configure to received service changes indications
any changes to the database during the time it has been disconnected
shall be indicated once it reconnects:

[bt] [DBG] sc_process: (0x004065b4) start 0x000a end 0x0014
[bt] [DBG] sc_save: (0x004065b4) peer b8:8a:60:d8:17:d7 (public)
 start 0x000a end 0x0014
[bt] [DBG] bt_gatt_connected: (0x00405240) conn 0x00405aa0
[bt] [DBG] gatt_ccc_changed: (0x00405240) ccc 0x00400b30 value 0x0002
[bt] [DBG] sc_ccc_cfg_changed: (0x00405240) value 0x0002
[bt] [DBG] sc_restore: (0x00405240) peer b8:8a:60:d8:17:d7 (public)
 start 0x000a end 0x0014
[bt] [DBG] sc_process: (0x004065b4) start 0x000a end 0x0014
[bt] [DBG] gatt_indicate: (0x004065b4) conn 0x00405aa0 handle 0x0008
[bt] [DBG] sc_indicate_rsp: (0x00405240) err 0x00

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>