ARM: dts: Extend existing CPU OPP for exynos5800

Fix CPU operating points for Exynos5800 (it use different
voltages than Exynos5420 and supports additional frequencies).
However don't use 2000MHz & 1900MHz OPPs (for A15 cores) and
1400MHz OPP (for A7 cores) for now as they are not available
on all boards.

Based on Hardkernel's kernel for ODROID-XU3 board.

Changes by Ben Gamari:
- Port to operating-points-v2

Cc: Doug Anderson <dianders@chromium.org>
Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Andreas Faerber <afaerber@suse.de>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Signed-off-by: Ben Gamari <ben@smart-cactus.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>