ASoC: SOF: Introduce widget use_count

Add a new field, use_count to struct snd_sof_widget to keep track
of the usage count for each widget. Since widgets can belong to
multiple pipelines, this field will ensure that the widget
is setup only when the first pipeline that needs it is started
and freed when the last pipeline that needs it is stopped. There is
no need to protect the widget use_count access as the core already
handles mutual exclusion at the PCM level.
Add a new helper sof_widget_free() to handle freeing the SOF
widgets and export the sof_widget_setup/free() functions.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20210927120517.20505-10-peter.ujfalusi@linux.intel.com


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