dt-bindings: clock: Add DT bindings for SMU of Toshiba Visconti TMPV770x SoC

Add device tree bindings for SMU (System Management Unit) controller of
Toshiba Visconti TMPV770x SoC series.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211025031038.4180686-3-nobuhiro1.iwamatsu@toshiba.co.jp
Signed-off-by: Stephen Boyd <sboyd@kernel.org>