bt_gatt_discover can be used to discover primary GATT service by UUID in
a selected handle range, after it attribute found the function callback
is called so the user can interact the attribute found and decide to
continue to the next or stop.
Change-Id: I37514f00c82ce5520d7a14757a6ff12ee34f0736
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>