netifd: replace backticks by $(...)

This replaces deprecated backticks by more versatile $(...) syntax.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

package/network/config/netifd/files/lib/network/config.sh

@@ -6,7 +6,7 @@
 find_config() {
 	local device="$1"
 	local ifdev ifl3dev ifobj
-	for ifobj in `ubus list network.interface.\*`; do
+	for ifobj in $(ubus list network.interface.\*); do
 		interface="${ifobj##network.interface.}"
 		(
 			json_load "$(ifstatus $interface)"