dm: sandbox: Allow selection of sample rate and channels

At present these parameters are hard-coded in the sdl interface code.
Allow them to be specified by the driver instead.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/include/asm/sdl.h b/arch/sandbox/include/asm/sdl.h
index 2799a8b..1027b59 100644
--- a/arch/sandbox/include/asm/sdl.h
+++ b/arch/sandbox/include/asm/sdl.h
@@ -71,9 +71,11 @@
 /**
  * sandbox_sdl_sound_init() - set up the sound system
  *
+ * @rate:	Sample rate to use
+ * @channels:	Number of channels to use (1=mono, 2=stereo)
  * @return 0 if OK, -ENODEV if no sound is available
  */
-int sandbox_sdl_sound_init(void);
+int sandbox_sdl_sound_init(int rate, int channels);
 
 #else
 static inline int sandbox_sdl_init_display(int width, int height,
@@ -112,7 +114,7 @@
 	return -ENODEV;
 }
 
-static inline int sandbox_sdl_sound_init(void)
+int sandbox_sdl_sound_init(int rate, int channels)
 {
 	return -ENODEV;
 }