Patch merged into coreboot/master: 0df877a arm64: use one stage_entry for all stages

the following patch was just integrated into master:
commit 0df877a65ac6563f1e46eea9e15e34a366d7105f
Author: Aaron Durbin 
Date:   Thu Jul 10 12:40:30 2014 -0500

arm64: use one stage_entry for all stages

Ramstage needs an assembly entry point for setting up
    the initial state of the CPU. Therefore, a function is
    provided, arm64_el3_startup(), that bootstraps the state
    of the processor, initializes the stack pointer, and
    branches to a defined entry symbol. To make this work
    without adding too much preprocessor macro conditions
    provide _stack and _estack for all the stages.

Currently the entry point after initialization is 'main',
    however it can be changed/extended to do more work such
    as seeding the stack contents with tombstones, etc.

It should be noted that romstage and bootblock weren't
    tested. Only ramstage is known to work.

BUG=chrome-os-partner:29923
    BRANCH=None
    TEST=Brought up 64-bit ramstage on rush.

Original-Change-Id: I1f07d5b6656e13e6667b038cdc1f4be8843d1960
    Original-Signed-off-by: Aaron Durbin 
    Original-Reviewed-on: https://chromium-review.googlesource.com/207262
    Original-Reviewed-by: Furquan Shaikh 
    (cherry picked from commit 7850ee3a7bf48c05f2e64147edb92161f8308f19)
    Signed-off-by: Marc Jones

Change-Id: Ia87697f49638c8c249215d441d95f1ec621e0949
    Reviewed-on: http://review.coreboot.org/8585
    Tested-by: build bot (Jenkins)
    Reviewed-by: Aaron Durbin

See http://review.coreboot.org/8585 for details.

-gerrit