P51XX: fix adb in twrp

On P51XX 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: Iecbb99b16b740ace480b53bb5963643426084e7a