ASoC: meson: add reset binding

ASoC: meson: add reset binding

The g12a audio subsystem, which is a derivative of the axg subsystem,
provides a dedicated reset line for each of the audio components.

The axg did not provide that and it is unclear if/when these reset are
required. The reset already helped solve a channel mapping issue on the
tdm formatter devices. Let's add the reset binding for the other
components, so we can describe this in DT. We'll use it later on
in the driver when/if needed.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20190905120120.31752-3-jbrunet@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>