soundwire: keep track of Masters in a stream

A multi link bankswitch can be done if the hardware supports and
the stream is handled by multiple Master(s).

This preparatory patch adds support to track m_rt in a stream.
Modifying m_rt_count and usage is added as part of the next patch.

Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/stream.c

@@ -865,6 +865,7 @@ struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name)
 	stream->name = stream_name;
 	INIT_LIST_HEAD(&stream->master_list);
 	stream->state = SDW_STREAM_ALLOCATED;
+	stream->m_rt_count = 0;
 
 	return stream;
 }

include/linux/soundwire/sdw.h

@@ -775,6 +775,7 @@ struct sdw_stream_params {
  * @master_list: List of Master runtime(s) in this stream.
  * master_list can contain only one m_rt per Master instance
  * for a stream
+ * @m_rt_count: Count of Master runtime(s) in this stream
  */
 struct sdw_stream_runtime {
 	char *name;
@@ -782,6 +783,7 @@ struct sdw_stream_runtime {
 	enum sdw_stream_state state;
 	enum sdw_stream_type type;
 	struct list_head master_list;
+	int m_rt_count;
 };
 
 struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name);