Bluetooth: GATT: Fix BT_GATT_AUTO_DISCOVER_CCC

When using BT_GATT_AUTO_DISCOVER_CCC if the ccc_handle is not set
bt_gatt_subscribe would initiate a discovery to locate the CCC handle
but instead of awaiting it to complete the code does proceed to call
gatt_write_ccc even with ccc_handle being 0x0000 which is invalid.

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

subsys/bluetooth/host/gatt.c

@@ -4129,10 +4129,7 @@ int bt_gatt_subscribe(struct bt_conn *conn,
 
 #if defined(CONFIG_BT_GATT_AUTO_DISCOVER_CCC)
 		if (!params->ccc_handle) {
-			err = gatt_ccc_discover(conn, params);
-			if (err) {
-				return err;
-			}
+			return gatt_ccc_discover(conn, params);
 		}
 #endif
 		err = gatt_write_ccc(conn, params->ccc_handle, params->value,