ARM: dts: Keep LDO4 always ON for exynos5250-arndale board

LDO4 regulator was getting disabled preventing the system from
going into low power states. Keep it always on to fix it.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>