ARM: dts: Add DISP1 power domain for exynos5420

The DISP1 power domain on Exynos5420 SoC includes the FIMD1, MIXER
and HDMI modules. Add a device node for this power domain and mark
these modules as consumer of the DISP1 power domain.

When a power domain is powered on and off, the input clocks of the
devices attached to it are reparented. So a reference to the input
and parent clocks of the devices are needed to manage that.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Kukjin Kim <kgene@kernel.org>