test/vhost: add "-g" for vhost_fuzz app

If the hugepage we use is 2MB, the numble of hugetlbfs will exceeds
the limit of 8. we must pass "-g" to vhost_fuzz app, which will pass
"--single-file-segments" to DPDK to create a single non-physically-
continuous hugetlbfs file for all its memory.

Here we pass "-g" to vhost_fuzz app which make the script work under
both 2MB and 1GB hugepage.

Signed-off-by: Richael Zhuang <richael.zhuang@arm.com>
Change-Id: I0287584c54f03a379957d6885c23e21a1fd10c4b
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/1148


Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>