firewall: change synflood_protect option name

The `syn_flood` option name is deprecated, `synflood_protect` should
be used instead. firewall3 and firewall4 both support this option since
a long time. LuCI already replaces the option name.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

Author: hauke

package/network/config/firewall/files/firewall.config

@@ -1,9 +1,9 @@
 config defaults
-	option syn_flood	1
+	option synflood_protect	1
 	option input		ACCEPT
 	option output		ACCEPT
 	option forward		REJECT
-	option fullcone	0
+	option fullcone		0
 # Uncomment this line to disable ipv6 rules
 #	option disable_ipv6	1
 
@@ -82,7 +82,7 @@ config rule
 config rule
 	option name		Allow-ICMPv6-Input
 	option src		wan
-	option proto	icmp
+	option proto		icmp
 	list icmp_type		echo-request
 	list icmp_type		echo-reply
 	list icmp_type		destination-unreachable