Add dt-schema documentation for Tesla FSD SoC clock controller.

Cc: linux-fsd@tesla.com
Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Link: https://lore.kernel.org/r/20220124141644.71052-4-alim.akhtar@samsung.comSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>