clk: samsung: Add dt bindings for Exynos4412 ISP clock controller

Some registers for the Exynos 4412 ISP (Camera subsystem) clocks are
located in the ISP power domain. Because those registers are also
located in a different memory region than the main clock controller,
support for them can be provided by a separate clock controller.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>