dt-bindings: clock: Add Ingenic JZ4755 CGU header

This will be used from the devicetree bindings to specify the clocks
that should be obtained from the jz4755-cgu driver.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Link: https://lore.kernel.org/r/20221027192024.484320-3-lis8215@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>