package/vsftpd: S70vsftpd: correct -x argument to start-stop-daemon

Fixes #13341

The -x / --exec start-stop-daemon option expects the path to the executable,
not just the name, leading to errors when running the init script:

Starting vsftpd: start-stop-daemon: unable to stat //vsftpd (No such file or directory)

Reported-by: tochansky@tochlab.net
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/vsftpd/S70vsftpd

@@ -9,12 +9,12 @@ DAEMON=/usr/sbin/$NAME
 case "$1" in
   start)
 	printf "Starting $DESC: "
-	start-stop-daemon -S -b -x $NAME
+	start-stop-daemon -S -b -x $DAEMON
 	echo "OK"
 	;;
   stop)
 	printf "Stopping $DESC: "
-	start-stop-daemon -K -x $NAME
+	start-stop-daemon -K -x $DAEMON
 	echo "OK"
 	;;
   restart|force-reload)