media: dt-bindings: samsung,exynos4210-csis: convert to dtschema

Convert the Samsung S5P/Exynos SoC series MIPI CSI-2 receiver (MIPI
CSIS) bindings to DT schema.  Changes during conversion - adjust to
existing DTS and Linux driver:
1. Add phys and power-domains.
2. Move samsung,csis-wclk property to the endpoint node.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>