dt-bindings: clock: samsung: convert Exynos7 to dtschema

Convert Samsung Exynos7 SoC clock controller bindings to DT schema
format.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220102115356.75796-4-krzysztof.kozlowski@canonical.com