ASoC: wm_adsp: Use DSP ops pointers to stop watchdog in error handlers

Whilst this isn't strictly necessary as the code is already DSP specific
better to use the pointers to avoid potential issues in the future if
one core ends up having multiple methods of stopping the watchdog.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>