COMPMID-2594: Graph example option parsing doens't fail on invalid values

Report warning/error on invalid argument depending on its importance.

Change-Id: I14a855c96d514e6b8a63a61e54410722affa06ce
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/1784
Reviewed-by: Kévin Petit
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/examples/graph_resnet50.cpp b/examples/graph_resnet50.cpp
index 7c9b95e..17506dc 100644
--- a/examples/graph_resnet50.cpp
+++ b/examples/graph_resnet50.cpp
@@ -43,6 +43,7 @@
     {
         // Parse arguments
         cmd_parser.parse(argc, argv);
+        cmd_parser.validate();
 
         // Consume common parameters
         common_params = consume_common_graph_parameters(common_opts);