arm64: dts: mediatek: cherry: Enable MT6360 sub-pmic on I2C7

arm64: dts: mediatek: cherry: Enable MT6360 sub-pmic on I2C7

All devices of the Cherry platform have a MT6360 sub-pmic,
providing two LDOs. Add the required node to enable the PMIC
but without regulators yet, as these will be added in a
later commit.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20220704101321.44835-10-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>