base-files: ignore initscript output in sysupgrade

Suppress output from `/etc/init.d/service enabled` to avoid corrupting
of the sysupgrade tarball.

Fixes: 0ad062a21b ("base-files: sysupgrade: add uci-defaults script disabling services #2")
Signed-off-by: Niall McGee <[email protected]>
Signed-off-by: Daniel Golle <[email protected]>

package/base-files/files/sbin/sysupgrade

@@ -273,7 +273,7 @@ create_backup_archive() {
 
 		if [ $ret -eq 0 ]; then
 			for service in /etc/init.d/*; do
-				if ! $service enabled; then
+				if ! $service enabled >/dev/null 2>&1; then
 				disabled="$disabled$service disable\n"
 				fi
 			done