ASoC: sta32x: make sta32x a gpio consumer for the reset GPIO

The reset GPIO on the STA32X Codecs is used to reset the Codec and clear
all registers. Also taking it down puts the IC in power save mode, so
we put the device in reset mode when we go to sleep.

Signed-off-by: Thomas Niederprüm <niederp@physik.uni-kl.de>
Signed-off-by: Mark Brown <broonie@kernel.org>