ALSA: doc: Fix spelling mistakes

correct Reatek to Realtek
Signed-off-by: huangjianghui <huangjianghui@uniontech.com>
Link: https://lore.kernel.org/r/20210610062036.30300-1-huangjianghui@uniontech.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

Documentation/sound/hd-audio/controls.rst

@@ -102,7 +102,7 @@ Conexant codecs
 ---------------
 
 Auto-Mute Mode
-  See Reatek codecs.
+  See Realtek codecs.
 
 
 Analog codecs