sound: Move Samsung-specific code into its own file

The i2s code is in fact Samsung-specific, but there might be other
implementation. Move this code into its own file. This makes it slightly
more obviously how to adjust the code to support another SoC, when someone
takes this task on.

Also drop non-FDT support, since it isn't used on Exynos 5.

Tested-by: Che-Liang Chiou <clchiou@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

include/configs/exynos5250-dt.h

@@ -51,6 +51,7 @@
 #define CONFIG_CMD_SOUND
 #ifdef CONFIG_CMD_SOUND
 #define CONFIG_SOUND
+#define CONFIG_I2S_SAMSUNG
 #define CONFIG_I2S
 #define CONFIG_SOUND_MAX98095
 #define CONFIG_SOUND_WM8994

include/sound.h

@@ -29,6 +29,15 @@ struct sound_codec_info {
 	enum en_sound_codec codec_type;
 };
 
+/*
+ * Generates square wave sound data for 1 second
+ *
+ * @param data          data buffer pointer
+ * @param size          size of the buffer
+ * @param freq          frequency of the wave
+ */
+void sound_create_square_wave(unsigned short *data, int size, uint32_t freq);
+
 /*
  * Initialises audio sub system
  * @param blob	Pointer of device tree node or NULL if none.