vold: add coldboot back and make sure it won't block booting

coldboot is needed when device rebooted with USB device attched
so Vold netlink won't miss the information.
This CL added back coldboot and moved down so that it won't block
vold cl and ccl threads.

Bug: 36007238
Test: reboot marlin with flash drive attached and flash drive is recognized
Change-Id: Ie39f348e97a8500515e394e386541289a91b2425
1 file changed