[ALSA] usb-audio - Fix a typo of CONFIG_PROC_FS

Fixed a typo of CONFIG_PROC_FS in usbaudio.c.
The stream proc file appears again.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/usb/usbaudio.c

@@ -2049,7 +2049,7 @@ static struct usb_driver usb_audio_driver = {
 };
 
 
-#if defined(CONFIG_PROCFS) && defined(CONFIG_SND_VERBOSE_PROCFS)
+#if defined(CONFIG_PROC_FS) && defined(CONFIG_SND_VERBOSE_PROCFS)
 
 /*
  * proc interface for list the supported pcm formats