ARM: dts: Add syscon phandle to the video-phy node for Exynos4

This is required to fix regression after introducing the PMU device
nodes required for the PMU driver modified in commit 14fc8b93
("ARM: EXYNOS: Add platform driver support for Exynos PMU").
This change is needed to make MIPI DSI displays and MIPI CSI-2
camera sensors working again on Exynos4 boards.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>