manta: Mount FunctionFS for adb

Change-Id: I420960f010a0aec65bfbf46049c46be001cef438
diff --git a/init.manta.usb.rc b/init.manta.usb.rc
index 63d0131..cadcbcb 100644
--- a/init.manta.usb.rc
+++ b/init.manta.usb.rc
@@ -7,6 +7,12 @@
     write /sys/class/android_usb/android0/f_rndis/vendorID 18d1
     write /sys/class/android_usb/android0/f_rndis/wceis 1
 
+on fs
+    mkdir /dev/usb-ffs 0770 shell shell
+    mkdir /dev/usb-ffs/adb 0770 shell shell
+    mount functionfs adb /dev/usb-ffs/adb uid=2000,gid=2000
+    write /sys/class/android_usb/android0/f_ffs/aliases adb
+
 on property:sys.usb.config=mtp
     write /sys/class/android_usb/android0/enable 0
     write /sys/class/android_usb/android0/idVendor 18d1