dt-bindings: clock: imx8mp: Add audiomix block control

dt-bindings: clock: imx8mp: Add audiomix block control

Unlike the other block control IPs in i.MX8M, the audiomix is mostly a
series of clock gates and muxes. Add DT bindings for this IP.

Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Tested-by: Adam Ford <aford173@gmail.com> #imx8mp-beacon-kit
Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Tested-by: Richard Leitner <richard.leitner@skidata.com>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/20230301163257.49005-3-marex@denx.de