fff-layer3-config: fix exit status of uci-default scripts

OpenWrt only removes uci-defaults scripts if the exit status of the
executed script is 0. Fix the exit code of the layer3-config migration
scripts so they are removed as intended.

Fixes: #313

Signed-off-by: Fabian Bläse <fabian@blaese.de>

src/packages/fff/fff-layer3-config/files/etc/uci-defaults/20-l3config-migrate-1-to-2

@@ -7,7 +7,7 @@
 BOARD="$(uci get board.model.name)"
 
 # only migrate appropriate config versions
-[ "$(uci -q get gateway.meta.config_version)" = "1" ] || exit 1
+[ "$(uci -q get gateway.meta.config_version)" = "1" ] || exit 0
 
 translate_ports() {
 	local vlan="$1"
@@ -77,3 +77,5 @@ esac
 
 uci set gateway.meta.config_version='2'
 uci commit gateway
+
+exit 0

src/packages/fff/fff-layer3-config/files/etc/uci-defaults/21-l3config-migrate-2-to-3

@@ -7,7 +7,7 @@
 BOARD="$(uci get board.model.name)"
 
 # only migrate appropriate config versions
-[ "$(uci -q get gateway.meta.config_version)" = "2" ] || exit 1
+[ "$(uci -q get gateway.meta.config_version)" = "2" ] || exit 0
 
 translate_ports() {
 	local vlan="$1"
@@ -74,3 +74,5 @@ esac
 
 uci set gateway.meta.config_version='3'
 uci commit gateway
+
+exit 0