sound: Retire SND_OLDSTEREO

This is a legacy option and does not serve a good purpose anymore.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Reviewed by:	markj
Differential Revision:	https://reviews.freebsd.org/D55933

sys/conf/NOTES

@@ -2175,15 +2175,11 @@ envvar		hint.gusc.0.flags="0x13"
 #                              integer/arithmetic. Slight increase of dynamic
 #                              range at a cost of possible slowdown.
 #
-# SND_OLDSTEREO                Only 2 channels are allowed, effectively
-#                              disabling multichannel processing.
-#
 options 	SND_DIAGNOSTIC
 options 	SND_FEEDER_MULTIFORMAT
 options 	SND_FEEDER_FULL_MULTIFORMAT
 options 	SND_FEEDER_RATE_HP
 options 	SND_PCM_64
-options 	SND_OLDSTEREO
 
 #
 # Cardbus

sys/conf/options

@@ -920,7 +920,6 @@ SND_FEEDER_MULTIFORMAT	opt_snd.h
 SND_FEEDER_FULL_MULTIFORMAT	opt_snd.h
 SND_FEEDER_RATE_HP	opt_snd.h
 SND_PCM_64		opt_snd.h
-SND_OLDSTEREO		opt_snd.h
 
 X86BIOS
 

sys/dev/sound/pcm/matrix.h

@@ -29,10 +29,7 @@
 #ifndef _SND_MATRIX_H_
 #define _SND_MATRIX_H_
 
-#undef SND_MULTICHANNEL
-#ifndef SND_OLDSTEREO
 #define SND_MULTICHANNEL	1
-#endif
 
 /*
  * XXX = unused, but part of the definition (will be used someday, maybe).