selftests: forwarding: lib: Add an autodefer variant of forwarding_enable()

Most forwarding tests invoke forwarding_enable() to enable the router and
forwarding_restore() to restore the original configuration. Add a helper,
adf_forwarding_enable(), which is like forwarding_enable(), but takes care
of scheduling the cleanup automatically.

Convert the tests that currently use defer to schedule the cleanup.

Signed-off-by: Petr Machata <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/forwarding/bridge_fdb_local_vlan_0.sh

···
 	h3=${NETIFS[p6]}
 
 	adf_vrf_prepare
-
-	forwarding_enable
-	defer forwarding_restore
+	adf_forwarding_enable
 
 	host_create "$h1" 192.0.2.1/28 2001:db8:1::1/64
 	host_create "$h2" 192.0.2.2/28 2001:db8:1::2/64

tools/testing/selftests/net/forwarding/lib.sh

···
 	sysctl_restore net.ipv4.conf.all.forwarding
 }
 
+adf_forwarding_enable()
+{
+	forwarding_enable
+	defer forwarding_restore
+}
+
 declare -A MTU_ORIG
 mtu_set()
 {

tools/testing/selftests/net/forwarding/vxlan_bridge_1q_mc_ul.sh

···
 	h3=${NETIFS[p6]}
 
 	adf_vrf_prepare
-
-	forwarding_enable
-	defer forwarding_restore
+	adf_forwarding_enable
 
 	adf_ip_link_add "v1$h2" type veth peer name "v2$h2"
 	adf_ip_link_add "v1$h3" type veth peer name "v2$h3"

tools/testing/selftests/net/forwarding/vxlan_reserved.sh

···
 	rp2=${NETIFS[p4]}
 
 	adf_vrf_prepare
-
-	forwarding_enable
-	defer forwarding_restore
+	adf_forwarding_enable
 
 	h1_create
 	switch_create