Patch merged into coreboot/master: rockchip/rk3399: Add pwm_regulator.c for pwm then ramp boot up cpu

the following patch was just integrated into master:
commit 61e6c4448c4d79035842434fb1eb3b4e9cd01c6d
Author: Eric Gao 
Date:   Fri Jul 29 12:34:32 2016 +0800

rockchip/rk3399: Add pwm_regulator.c for pwm then ramp boot up cpu

Before, we calculate the pwm duties for cpu cores and centerlogic by
    hand, adding pwm_regulator.c to handle this. The default pwm design
    min/max voltage may be different between revs.

With the pwm regulator, this patch changes the little cpu frequency from
    600M to 1512M, and raises CPU voltage to 1.2V correspondingly.

This also means we decide to drop the ES1 because it may fail to
    bootup with 1.5G ~ 1.2v.

BRANCH=none
    BUG=chrome-os-partner:54376,chrome-os-partner:54862
    TEST=Bootup on kevin board

Change-Id: Id04c176bddfb9cdf3d25b65736e40249a85f6aa1
    Signed-off-by: Martin Roth 
    Original-Commit-Id: ee4365c787ec523b7ee1028ea100dcfbb331b3a9
    Original-Change-Id: Ide75bbd92d1cbb14f934baeec0e38862bc08402b
    Original-Signed-off-by: Eric Gao 
    Original-Signed-off-by: Shunqian Zheng 
    Original-Reviewed-on: https://chromium-review.googlesource.com/364410
    Original-Reviewed-by: Julius Werner 
    Reviewed-on: https://review.coreboot.org/16368
    Tested-by: build bot (Jenkins)
    Reviewed-by: Aaron Durbin

See https://review.coreboot.org/16368 for details.

-gerrit