[source] netifd: fix fw3 warnings in dhcp script

[LEDE Commits]

jow pushed a commit to source.git, branch lede-17.01:
https://git.lede-project.org/7fb03d96105ae3d42c422383bdb36eff76d403e0

commit 7fb03d96105ae3d42c422383bdb36eff76d403e0
Author: Hans Dedecker <dedeckeh at gmail.com>
AuthorDate: Sun Apr 2 21:13:08 2017 +0200

    netifd: fix fw3 warnings in dhcp script
    
    Fix fw3 warnings in dhcp script in case fw3 is not enabled
    
    Signed-off-by: Hans Dedecker <dedeckeh at gmail.com>
    (cherry picked from commit 20e40db524fb6c391f47619b18bf36bf7932478a)
---
 package/network/config/netifd/files/lib/netifd/dhcp.script | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package/network/config/netifd/files/lib/netifd/dhcp.script b/package/network/config/netifd/files/lib/netifd/dhcp.script
index b3a61e2..e841f91 100755
--- a/package/network/config/netifd/files/lib/netifd/dhcp.script
+++ b/package/network/config/netifd/files/lib/netifd/dhcp.script
@@ -60,7 +60,7 @@ setup_interface () {
 		ip6rd="${ip6rd#* }"
 		local ip6rdbr="${ip6rd%% *}"
 
-		[ -n "$ZONE" ] || ZONE=$(fw3 -q network $INTERFACE)
+		[ -n "$ZONE" ] || ZONE=$(fw3 -q network $INTERFACE 2>/dev/null)
 		[ -z "$IFACE6RD" -o "$IFACE6RD" = 1 ] && IFACE6RD=${INTERFACE}_6
 
 		json_init