ASoC: samsung: i2s: Document clocks macros

Document clocks macros with their description
from 'Documentation/devicetree/bindings/sound/samsung-i2s.txt'

Signed-off-by: Maciej Falkowski <[e-mail]>
Signed-off-by: Marek Szyprowski <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

include/dt-bindings/sound/samsung-i2s.h

···
 #ifndef _DT_BINDINGS_SAMSUNG_I2S_H
 #define _DT_BINDINGS_SAMSUNG_I2S_H
 
-#define CLK_I2S_CDCLK		0
-#define CLK_I2S_RCLK_SRC	1
-#define CLK_I2S_RCLK_PSR	2
+#define CLK_I2S_CDCLK		0 /* the CDCLK (CODECLKO) gate clock */
+
+#define CLK_I2S_RCLK_SRC	1 /* the RCLKSRC mux clock (corresponding to
+				   * RCLKSRC bit in IISMOD register)
+				   */
+
+#define CLK_I2S_RCLK_PSR	2 /* the RCLK prescaler divider clock
+				   * (corresponding to the IISPSR register)
+				   */
 
 #endif /* _DT_BINDINGS_SAMSUNG_I2S_H */