soundwire: bus: squelch error returned by mockup devices

All read and writes from/to SoundWire mockup devices will return
-ENODATA/Command_Ignored, this patch forces a Command_OK result to let
the bus perform the required configurations, e.g. for the Data Ports,
which will only have an effect on the Master side.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20210714032209.11284-8-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/bus.c

@@ -390,7 +390,10 @@ sdw_nread_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 	if (ret < 0)
 		return ret;
 
-	return sdw_transfer(slave->bus, &msg);
+	ret = sdw_transfer(slave->bus, &msg);
+	if (slave->is_mockup_device)
+		ret = 0;
+	return ret;
 }
 
 static int
@@ -404,7 +407,10 @@ sdw_nwrite_no_pm(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 	if (ret < 0)
 		return ret;
 
-	return sdw_transfer(slave->bus, &msg);
+	ret = sdw_transfer(slave->bus, &msg);
+	if (slave->is_mockup_device)
+		ret = 0;
+	return ret;
 }
 
 int sdw_write_no_pm(struct sdw_slave *slave, u32 addr, u8 value)