ASoC: SOF: Intel: Baytrail: fix 'defined but not used' warnings

ASoC: SOF: Intel: Baytrail: fix 'defined but not used' warnings

With the allmodconfig option, CONFIG_SND_SOC_SOF_BAYTRAIL is disabled
due to mutual exclusion with the legacy driver. This generates
'defined by not used' warnings.

suspend/resume/remove are only supported for Baytrail for now, so move
the code under the CONFIG_SND_SOC_SOF_BAYTRAIL checks.

Fixes: ddcccd543f5d ("ASoC: SOF: Intel: byt: Add PM callbacks")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200529150408.17236-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>