mgcp_client_vty: fixing docstring

The docstring in the VTY command that is used to remove MGCP client
instances lacks the NO_STR constant.

Change-Id: I53f3e763a77ed8be78c5a51b1472f4b70bade9d4
Related: SYS#5091
diff --git a/src/libosmo-mgcp-client/mgcp_client_vty.c b/src/libosmo-mgcp-client/mgcp_client_vty.c
index 34502af..8719e3c 100644
--- a/src/libosmo-mgcp-client/mgcp_client_vty.c
+++ b/src/libosmo-mgcp-client/mgcp_client_vty.c
@@ -374,7 +374,7 @@
 
 DEFUN_ATTR(cfg_no_mgw,
 	   cfg_no_mgw_cmd,
-	   "no mgw <0-255>", "Select a MGCP client config to remove\n" "reference number", CMD_ATTR_IMMEDIATE)
+	   "no mgw <0-255>", NO_STR "Select a MGCP client config to remove\n" "reference number\n", CMD_ATTR_IMMEDIATE)
 {
 	int nr = atoi(argv[0]);
 	struct mgcp_client_pool_member *pool_member;