ASoC: adau17x1: Do not reload dsp-fw if samplerate has not changed

Reloading fw causes an audiable popping sound, we can avoid this
by not reloading if the samplerate is the same as before.

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>