dt-bindings: clock: Add bindings for Exynos7885 CMU_FSYS

CMU_FSYS clock domain provides clocks for MMC (MMC_CARD, MMC_EMBD,
MMC_SDIO), and USB30DRD.

Add clock indices and bindings documentation for CMU_FSYS domain.

Signed-off-by: David Virag <virag.david003@gmail.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220601233743.56317-2-virag.david003@gmail.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>