net/mwan3: fix ubus output for mwan3track running state

Fix ubus output for mwan3track running state

Signed-off-by: Florian Eckert <fe@dev.tdt.de>

net/mwan3/files/usr/libexec/rpcd/mwan3

@@ -37,7 +37,7 @@ get_mwan3_status() {
 	local pid
 
 	if [ "${iface}" = "${iface_select}" ] || [ "${iface_select}" = "" ]; then
-		pid="$(pgrep -f "mwan3track $iface_selected")"
+		pid="$(pgrep -f "mwan3track $iface")"
 		if [ "${pid}" != "" ]; then
 			running="1"
 		fi