soundwire: depend on ACPI || OF

Now devicetree is supported for probing soundwire as well.

On platforms built with !ACPI !OF (ie s390x) the device still cannot be
probed and gives a build warning.

Cc: stable@vger.kernel.org
Fixes: a2e48458 ("soundwire: core: add device tree support for slave devices")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Link: https://lore.kernel.org/r/0b89b4ea16a93f523105c81a2f718b0cd7ec66f2.1570097621.git.msuchanek@suse.deSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/Kconfig

@@ -5,7 +5,7 @@
 
 menuconfig SOUNDWIRE
 	tristate "SoundWire support"
-	depends on ACPI
+	depends on ACPI || OF
 	help
 	  SoundWire is a 2-Pin interface with data and clock line ratified
 	  by the MIPI Alliance. SoundWire is used for transporting data