media: samsung: exynos4-is: drop simple-bus from compatibles

The FIMC camera node wrapper is not a bus, so using simple-bus fallback
compatible just to instantiate its children nodes was never correct.
Driver should explicitly populate all its children devices.

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