Log wpa_supplicant messages to syslog.

--- a/wpa_supplicant/dbus-wpa_supplicant.service
+++ b/wpa_supplicant/dbus-wpa_supplicant.service
@@ -1,4 +1,4 @@
 [D-BUS Service]
 Name=fi.epitest.hostap.WPASupplicant
-Exec=/sbin/wpa_supplicant -u
+Exec=/sbin/wpa_supplicant -u -s
 User=root
