soundwire: Add bank switch routine

SoundWire supports two registers banks. So, program the alternate bank
with new configuration and then performs bank switch.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/bus.c

@@ -78,6 +78,13 @@ int sdw_add_bus_master(struct sdw_bus *bus)
 		return ret;
 	}
 
+	/*
+	 * Default active bank will be 0 as out of reset the Slaves have
+	 * to start with bank 0 (Table 40 of Spec)
+	 */
+	bus->params.curr_bank = SDW_BANK0;
+	bus->params.next_bank = SDW_BANK1;
+
 	return 0;
 }
 EXPORT_SYMBOL(sdw_add_bus_master);