rmnetcli: Fix potential SEGV

Input check all params for flowactivate to make
sure SEGV is not possible.

CRs-Fixed: 2701493
Change-Id: I303e2701f37779d1262f5102f342974f63fd01cc
diff --git a/rmnetctl/cli/rmnetcli.c b/rmnetctl/cli/rmnetcli.c
index 8b60127..11184d7 100644
--- a/rmnetctl/cli/rmnetcli.c
+++ b/rmnetctl/cli/rmnetcli.c
@@ -427,6 +427,7 @@
 			_RMNETCLI_CHECKNULL(argv[3]);
 			_RMNETCLI_CHECKNULL(argv[4]);
 			_RMNETCLI_CHECKNULL(argv[5]);
+			_RMNETCLI_CHECKNULL(argv[6]);
 
 			return_code = rtrmnet_activate_flow(handle, argv[1], argv[2],
 							    _STRTOUI8(argv[3]),