ARM: dts: exynos: Move HDMI PHY node from boards to exynos5250.dtsi

All Exynos 5250 SoCs have HDMI PHY connected via dedicated I2C bus (bus
number 8), so HDMI PHY should be defined in exynos5250.dtsi instead of
duplicating it in every board, which enables HDMI support.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>