ASoC: SOF: (cosmetic) use the "bool" type where it makes sense

Several fields in struct snd_sof_dev are used as boolean flags, use
the "bool" type for them.

Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200824200912.46852-3-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>