[PATCH -next] soundwire: Fix -Wunused-function warning

[YueHaibing]

If CONFIG_ACPI is not set, gcc warning this:

drivers/soundwire/slave.c:16:12: warning:
 'sdw_slave_add' defined but not used [-Wunused-function]

move them to #ifdef CONFIG_ACPI block.

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 drivers/soundwire/slave.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
index f39a581..34c7e65 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -6,6 +6,7 @@
 #include <linux/soundwire/sdw_type.h>
 #include "bus.h"
 
+#if IS_ENABLED(CONFIG_ACPI)
 static void sdw_slave_release(struct device *dev)
 {
 	struct sdw_slave *slave = dev_to_sdw_dev(dev);
@@ -60,7 +61,6 @@ static int sdw_slave_add(struct sdw_bus *bus,
 	return ret;
 }
 
-#if IS_ENABLED(CONFIG_ACPI)
 /*
  * sdw_acpi_find_slaves() - Find Slave devices in Master ACPI node
  * @bus: SDW bus instance
-- 
2.7.4