[ALSA] Optimize for config without PROC_FS (pci drivers)

Optimize the code when compiled without CONFIG_PROC_FS for some pci drivers.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/ca0106/ca0106_proc.c b/sound/pci/ca0106/ca0106_proc.c
index 94b6225..6375727 100644
--- a/sound/pci/ca0106/ca0106_proc.c
+++ b/sound/pci/ca0106/ca0106_proc.c
@@ -77,6 +77,8 @@
 #include "ca0106.h"
 
 
+#ifdef CONFIG_PROC_FS
+
 struct snd_ca0106_category_str {
 	int val;
 	const char *name;
@@ -459,3 +461,4 @@
 	return 0;
 }
 
+#endif /* CONFIG_PROC_FS */