onclite: Switch to two-stage init mounting

* Stop handling vendor mounting from kernel, first stage init is gonna
  do that, together with system (which is now /system)
* Use correct mount flags coming from kernel dts
* Move system and vendor mount points to /dev/block/by-name/, we don't
  have bootdevice symlink to that point in init
* Copy fstab to recovery for first stage init

Change-Id: Iaa0ecc3f13c3cfd3fe357ca509549d0f68a29cf0