Fix bug in IMDS ipv6 lockdown

This commit fixes bug in aws#1459

Signed-off-by: Hanwen <[email protected]>

Author: hanwen-cluster

cookbooks/aws-parallelcluster-config/files/default/imds/imds-access.sh

@@ -35,7 +35,7 @@ EOF
 }
 
 function iptables_delete() {
-  local $iptables_command=$1
+  local iptables_command=$1
   local chain=$2
   local destination=$3
   local jump=$4