ALSA: emux: Fix/cleanup old ifdef CONFIG_PROC_FS

Build emux_proc.o and drop the unneeded ifdefs.
Replace the left CONFIG_PROC with the new CONFIG_SND_PROC_FS.

Along with this, fix the build of emux_oss.o in Makefile, too.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/include/sound/emux_synth.h b/include/sound/emux_synth.h
index fb81f37..a0a40b7 100644
--- a/include/sound/emux_synth.h
+++ b/include/sound/emux_synth.h
@@ -125,7 +125,7 @@
 
 	struct snd_util_memhdr *memhdr;	/* memory chunk information */
 
-#ifdef CONFIG_PROC_FS
+#ifdef CONFIG_SND_PROC_FS
 	struct snd_info_entry *proc;
 #endif