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 <lizhijian@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>