ipmi-net: Restore the persisted iptables filter

If the persisted iptables filter exist restore the filter.

Tested: The iptables filter is restored when the phosphor-ipmi-net

Change-Id: I8486f2928374ae6ea1b164426c405462ba0eabc8
Signed-off-by: Tom Joseph <tomjoseph@in.ibm.com>
diff --git a/recipes-phosphor/ipmi/phosphor-ipmi-net/phosphor-ipmi-net.service b/recipes-phosphor/ipmi/phosphor-ipmi-net/phosphor-ipmi-net.service
index 2d61b90..6b836b6 100644
--- a/recipes-phosphor/ipmi/phosphor-ipmi-net/phosphor-ipmi-net.service
+++ b/recipes-phosphor/ipmi/phosphor-ipmi-net/phosphor-ipmi-net.service
@@ -11,6 +11,8 @@
 After=mapper-wait@-xyz-openbmc_project-control-host0-restriction_mode.service
 
 [Service]
+Environment=IPTABLESRULE=/var/lib/iptables_rules
+ExecStartPre=/usr/bin/env ipmi-net-firewall.sh
 ExecStart=/usr/bin/env netipmid
 SyslogIdentifier=netipmid
 Restart=always