fix adb root in recovery

recovery's init.rc was missing lines that made adb root work.

Change-Id: I300e6997e3b5cb9c7b542b2012eed61deb2550f1
diff --git a/etc/init.rc b/etc/init.rc
index e2b4236..fad32df 100644
--- a/etc/init.rc
+++ b/etc/init.rc
@@ -60,3 +60,7 @@
     write /sys/class/android_usb/android0/enable 1
     start adbd
 
+on property:service.adb.root=1
+    write /sys/class/android_usb/android0/enable 0
+    restart adbd
+    write /sys/class/android_usb/android0/enable 1