soundwire: bus: demote clock stop prepare log to dev_dbg()

There is no real reason to provide this information except for debug
sessions, hence dev_dbg() is a better fit.

Reported-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

Author: plbossart

drivers/soundwire/bus.c

@@ -906,8 +906,8 @@ static int sdw_bus_wait_for_clk_prep_deprep(struct sdw_bus *bus, u16 dev_num)
 			return val;
 		}
 		if (!val) {
-			dev_info(bus->dev, "clock stop prep/de-prep done slave:%d",
-				 dev_num);
+			dev_dbg(bus->dev, "clock stop prep/de-prep done slave:%d",
+				dev_num);
 			return 0;
 		}