selftests: net: remove meaningless help option

$ ./fcnal-test.sh -t help
Test names: help

Looks it intent to list the available tests but it didn't do the right
thing. I will add another option the do that in the later patch.

Signed-off-by: Li Zhijian <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

tools/testing/selftests/net/fcnal-test.sh

···
 	# setup namespaces and config, but do not run any tests
 	setup)		 setup; exit 0;;
 	vrf_setup)	 setup "yes"; exit 0;;
-
-	help)            echo "Test names: $TESTS"; exit 0;;
 	esac
 done