[ALSA] Fix OSS documentation about 3bytes format

Now the OSS emulation supports 3bytes format, too.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

Documentation/sound/alsa/OSS-Emulation.txt

@@ -303,10 +303,3 @@ ICE1712 supports only the unconventional format, interleaved
 the buffer as the conventional (mono or 2-channels, 8 or 16bit) format
 on OSS.
 
-USB devices
------------
-Some USB devices support only 24bit format packed in 3bytes.  This
-format is not supported by OSS and no conversion is provided by kernel
-OSS emulation.  You can use the user-space OSS emulation via libaoss
-instead.
-