ARM: dts: exynos: add missing HDMI supplies on SMDK5420

Add required VDD supplies to HDMI block on SMDK5420.  Without them, the
HDMI driver won't probe.  Because of lack of schematics, use same
supplies as on Arndale Octa and Odroid XU3 boards (voltage matches).

Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Link: https://lore.kernel.org/r/20220208171823.226211-3-krzysztof.kozlowski@canonical.com