P31XX: fix adb in twrp

On P31XX we need
    write /sys/class/android_usb/android0/idVendor 04e8
    write /sys/class/android_usb/android0/idProduct 685e
inside init.rc to get adb work correctly.

Change-Id: I135a27873e83bb4a8d19c052c320fda81460d25a