Bluetooth: GATT: Make BT_GATT_CHARACTERISTIC declare its value

This ensures the every characteristic has a value attribute declared
with the same UUID since the old macro did not declare the value the
application would normally have to declare one itself using a different
UUID which is not allowed.

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