[ALSA] Fix Oops at rmmod with CONFIG_SND_VERBOSE_PROCFS=n

Fixed Oops at rmmod with CONFIG_SND_VERBOSE_PROCFS=n.
Add ifdef to struct fields for optimization and better compile
checks.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index f3a07fb..4262a1c 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -142,7 +142,7 @@
 
 config SND_VERBOSE_PROCFS
 	bool "Verbose procfs contents"
-	depends on SND
+	depends on SND && PROC_FS
 	default y
 	help
 	  Say Y here to include code for verbose procfs contents (provides
@@ -175,7 +175,7 @@
 config SND_PCM_XRUN_DEBUG
 	bool "Enable PCM ring buffer overrun/underrun debugging"
 	default n
-	depends on SND_DEBUG
+	depends on SND_DEBUG && SND_VERBOSE_PROCFS
 	help
 	  Say Y to enable the PCM ring buffer overrun/underrun debugging.
 	  It is usually not required, but if you have trouble with