ASoC: adau17x1: Handling of DSP_RUN register during fw setup

DSP_RUN needs to be disabled during firmware write otherwise
we can end up with undefined behavior if writing to a dsp which
is already running firmware.

Signed-off-by: Danny Smith <dannys@axis.com>
Signed-off-by: Robert Rosengren <robert.rosengren@axis.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>