client/gatt: Fix memory leak issues

client/gatt: Fix memory leak issues

While performing the static tool analysis using coverity tool
found following reports

Error: RESOURCE_LEAK (CWE-772):
bluez-5.64/client/gatt.c:1531: leaked_storage: Variable "service"
going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK (CWE-772):
bluez-5.64/client/gatt.c:2626: leaked_storage: Variable "chrc"
going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK (CWE-772):
bluez-5.64/client/gatt.c:2906: leaked_storage: Variable "desc"
going out of scope leaks the storage it points to.

Signed-off-by: Manika Shrivastava <manika.sh@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>