ARM: dts: exynos: move DP and MIPI phys to PMU node in Exynos5420

ARM: dts: exynos: move DP and MIPI phys to PMU node in Exynos5420

The DisplayPort and MIPI phys are actually part of the Power Management
Unit system controller.  They do not have their own address space, thus
keeping the nodes under soc causes warnings:

  exynos5420-smdk5420.dtb: soc: dp-video-phy: {'compatible': ['samsung,exynos5420-dp-video-phy'],
    'samsung,pmu-syscon': [[11]], '#phy-cells': [[0]], 'phandle': [[16]]} should not be valid under {'type': 'object'}

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20230127194057.186458-7-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>