test/vmd: return zero after sucessful test run

After successful completion the test now returns with zero status code.

Change-Id: Id0ede49d3c7b6bdbcc0603dd65e98f0bad004219
Signed-off-by: Konrad Sztyber <konrad.sztyber@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/470663
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Wojciech Malikowski <wojciech.malikowski@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

test/vmd/vmd.sh

@@ -9,7 +9,7 @@ rpc_py=$rootdir/scripts/rpc.py
 
 pci_devs=$($rootdir/app/spdk_lspci/spdk_lspci | grep "NVMe disk behind VMD" | awk '{print $1}')
 
-if [ -z $pci_devs ]; then
+if [ -z "$pci_devs" ]; then
         echo "Couldn't find any NVMe device behind a VMD."
         exit 1
 fi
@@ -54,4 +54,7 @@ for bdf in $pci_devs; do
 	$rpc_py bdev_nvme_attach_controller -b NVMe_$bdf -t PCIe -a $bdf
 done
 
+trap - SIGINT SIGTERM EXIT
+killprocess $svcpid
+
 timing_exit vmd