ARM: dts: exynos: add HDMI controller phandle to exynos4.dtsi

Add the new hdmi phandle to exynos4.dtsi. This phandle is needed by the
s5p-cec driver to initialize the CEC notifier framework.

Tested with my Odroid U3.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>