fix shell check error

Signed-off-by: Periyasamy Palanisamy <[email protected]>

build/standalone/configure-ovs.sh

@@ -1,4 +1,5 @@
 #!/bin/sh
+
 ovs_version=$(ovs-vsctl -V | grep ovs-vsctl | awk '{print $4}')
 ovs_db_version=$(ovsdb-tool schema-version /usr/share/openvswitch/vswitch.ovsschema)
 
@@ -10,6 +11,6 @@ ovs-vsctl --no-wait -- set Open_vSwitch . db-version="${ovs_db_version}"
 ovs-vsctl --no-wait -- set Open_vSwitch . ovs-version="${ovs_version}"
 ovs-vsctl --no-wait -- set Open_vSwitch . system-type="docker-ovs"
 ovs-vsctl --no-wait -- set Open_vSwitch . system-version="0.1"
-ovs-vsctl --no-wait -- set Open_vSwitch . external-ids:system-id=`cat /proc/sys/kernel/random/uuid`
+ovs-vsctl --no-wait -- set Open_vSwitch . external-ids:system-id=$(cat /proc/sys/kernel/random/uuid)
 ovs-vsctl --no-wait -- set-manager ptcp:6640
 ovs-appctl -t ovsdb-server ovsdb-server/add-remote db:Open_vSwitch,Open_vSwitch,manager_options