arm64: dts: imx8mq-reform2: add sound support

This adds sound support to the Reform2.

It differs from the downstream implementation in that the codec
is used as the BCLK and FSYNC master and the i.MX8MQ only supplies
a fixed 25MHz MCLK from the oscillator. This allows to support
a wider range of audio rates by using the codec PLL and to shut
down the audio PLLs on the i.MX8MQ SoC side.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>