arm: convert to new device tree usage
arm: convert to new device tree usage

This also includes reading the nonvolatile storage from disk instead of
through the device-tree, since it's not updated there.

BUG=none
TEST=read and write a few crossystem variables

Change-Id: I6836a6eb0c92a0560dd393e694690a694bdb77a6
Reviewed-on: http://gerrit.chromium.org/gerrit/4078
Tested-by: Olof Johansson <13dc431ca3b0f062f888def8f8ec4662ec608f7d@chromium.org>
Reviewed-by: Rong Chang <3a05493f7adfb36d203f663b3bc2ba30e9d6284f@chromium.org>

acorn-marvell/vboot_reference,acorn-marvell/vboot_reference,marineam/seismograph,ccaapton/vboot_reference,coreboot/vboot,marineam/seismograph,ccaapton/vboot_reference,ccaapton/vboot_reference,marineam/seismograph,marineam/seismograph,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,coreboot/vboot,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,ccaapton/vboot_reference,ionave/seismograph,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,coreboot/vboot,ionave/seismograph,geekboxzone/mmallow_external_vboot_reference,ionave/seismograph,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot