arm64: dts: qcom: msm8998: Configure the MultiMedia Clock Controller (MMCC)

The MSM8998 MMCC is supported and has a driver: configure it as a
preparation for a later enablement of multimedia nodes (mdp, venus
and others).

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210901183123.1087392-1-angelogioacchino.delregno@somainline.org