dt-bindings: clock: mediatek: Document reset cells for MT8188 sys

The MT8188 sys clocks embed a reset controller: add #reset-cells
to the binding to allow using resets.

Fixes: 1086a531 ("dt-bindings: clock: mediatek: Add new MT8188 clock")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240619085322.66716-2-angelogioacchino.delregno@collabora.com


Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>