dt-bindings: display/msm/dsi-phy: Add header with exposed clock IDs

DSI phys, from earliest (28 nm) up to newest (3 nm) generation, provide
two clocks.  The respective clock ID is used by drivers and DTS, so it
should be documented as explicit ABI.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/634146/
Link: https://lore.kernel.org/r/20250127132105.107138-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>