exynos5: Don't potentially undervoltage the CPU

exynos5: Don't potentially undervoltage the CPU

For snow when chainloading u-boot the CPU seems to be running at full
speed. The lower CPU voltage seems to be ok for u-boot, but when booting
linux (bringing up all cores) I'm seeing random crashes.

Bump the voltage up to a level that's safe for all cpu frequencies.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>