dt-bindings: clock: Add support for the SDM630 and SDM660 mmcc

Document the multimedia clock controller found on SDM630/660.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Link: https://lore.kernel.org/r/20210113183817.447866-5-angelogioacchino.delregno@somainline.org


Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>