ARM: dts: Add vmmc regulator support for Arndale board

Added vmmc regulator node to Arndale DT file.

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