shared/gatt-client: Fix removing services with no attributes

shared/gatt-client: Fix removing services with no attributes

This patch comes from below commit of upstream.

commit d6c07ecf22ba60d6dd1b7302281eb32e1f278ca7
Author: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date:   Tue May 30 14:40:56 2017 +0300

shared/gatt-client: Fix removing services with no attributes

If a service has no attributes, like IPSS, just mark it as active and
skip doing any attribute discover.

Change-Id: I08eac1787f95fd091470496764bf8cf9924c0520
Signed-off-by: Seungyoun Ju <sy39.ju@samsung.com>
Signed-off-by: DoHyun Pyun <dh79.pyun@samsung.com>