ARM: dts: exynos: drop simple-bus from FIMC in Exynos4

ARM: dts: exynos: drop simple-bus from FIMC in Exynos4

The FIMC camera node wrapper is not a bus, so using simple-bus fallback
compatible just to instantiate its children nodes was never correct.
Dropping simple-bus node fixes warnings:

  exynos4210-smdkv310.dtb: camera: $nodename:0: 'camera' does not match '^([a-z][a-z0-9\\-]+-bus|bus|localbus|soc|axi|ahb|apb)(@.+)?$'

The change is not backwards compatible and expects the FIMC driver to
populate its children.

Link: https://lore.kernel.org/r/20230207193254.550236-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>