ARM: dts: Set BUCK7 as always on for Origen board

The LDO for LCD driver is currently not handled by any of the drivers.
This disables the LDO during booting time. To fix this, the LDO
is forced to enabled always.

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