ALSA: opl4: Use IS_REACHABLE()

Rewrite the complex ifdef condition with IS_REACHABLE().
The ifdef in opl4_local.h was without defined(MODLE) check, but this
is likely the oversight.  Use IS_REACHABLE() here as well.
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/opl4/opl4_lib.c

@@ -153,7 +153,7 @@ static int snd_opl4_detect(struct snd_opl4 *opl4)
 	return 0;
 }
 
-#if defined(CONFIG_SND_SEQUENCER) || (defined(MODULE) && defined(CONFIG_SND_SEQUENCER_MODULE))
+#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
 static void snd_opl4_seq_dev_free(struct snd_seq_device *seq_dev)
 {
 	struct snd_opl4 *opl4 = seq_dev->private_data;
@@ -249,7 +249,7 @@ int snd_opl4_create(struct snd_card *card,
 	snd_opl4_create_mixer(opl4);
 	snd_opl4_create_proc(opl4);
 
-#if defined(CONFIG_SND_SEQUENCER) || (defined(MODULE) && defined(CONFIG_SND_SEQUENCER_MODULE))
+#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
 	opl4->seq_client = -1;
 	if (opl4->hardware < OPL3_HW_OPL4_ML)
 		snd_opl4_create_seq_dev(opl4, seq_device);

sound/drivers/opl4/opl4_local.h

@@ -184,7 +184,7 @@ struct snd_opl4 {
 #endif
 	struct mutex access_mutex;
 
-#if defined(CONFIG_SND_SEQUENCER) || defined(CONFIG_SND_SEQUENCER_MODULE)
+#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
 	int used;
 
 	int seq_dev_num;