USB: Put back the composition filler

This is used in some compositions (rndis,adb in particular)

Change-Id: Id301f6de94531a40970e9b352c8aaebe16fd6d51

rootdir/etc/init.qcom.usb.rc

@@ -34,6 +34,7 @@ on boot
     write /sys/class/android_usb/android0/iSerial ${ro.serialno}
     write /sys/class/android_usb/android0/iManufacturer ${ro.product.manufacturer}
     write /sys/class/android_usb/android0/iProduct ${ro.product.model}
+    setprop persist.sys.usb.config.extra none
 
 on charger
     setprop sys.usb.config mass_storage