ALSA: opl4: Fix / cleanup ifdef CONFIG_PROC_FS

Some are replaced with the new ifdef CONFIG_SND_PROC_FS.  Some are
removed by building opl4_proc.o conditionally.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/drivers/opl4/Makefile b/sound/drivers/opl4/Makefile
index b94009b..c8eaa43 100644
--- a/sound/drivers/opl4/Makefile
+++ b/sound/drivers/opl4/Makefile
@@ -3,7 +3,8 @@
 # Copyright (c) 2001 by Jaroslav Kysela <perex@perex.cz>
 #
 
-snd-opl4-lib-objs := opl4_lib.o opl4_mixer.o opl4_proc.o
+snd-opl4-lib-objs := opl4_lib.o opl4_mixer.o
+snd-opl4-lib-$(CONFIG_SND_PROC_FS) += opl4_proc.o
 snd-opl4-synth-objs := opl4_seq.o opl4_synth.o yrw801.o
 
 obj-$(CONFIG_SND_OPL4_LIB) += snd-opl4-lib.o