ASoC: use DEFINE_SHOW_ATTRIBUTE() to decrease code duplication

There is some duplicate code in soc-core.c, and the kernel provides
DEFINE_SHOW_ATTRIBUTE() helper macro to decrease it in seq_file.h.
Signed-off-by: NPeng Donglin <dolinux.peng@gmail.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/soc-core.c

@@ -349,7 +349,7 @@ static void soc_init_codec_debugfs(struct snd_soc_component *component)
 			"ASoC: Failed to create codec register debugfs file\n");
 }
 
-static int codec_list_seq_show(struct seq_file *m, void *v)
+static int codec_list_show(struct seq_file *m, void *v)
 {
 	struct snd_soc_codec *codec;
 
@@ -362,20 +362,9 @@ static int codec_list_seq_show(struct seq_file *m, void *v)
 
 	return 0;
 }
+DEFINE_SHOW_ATTRIBUTE(codec_list);
 
-static int codec_list_seq_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, codec_list_seq_show, NULL);
-}
-
-static const struct file_operations codec_list_fops = {
-	.open = codec_list_seq_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
-
-static int dai_list_seq_show(struct seq_file *m, void *v)
+static int dai_list_show(struct seq_file *m, void *v)
 {
 	struct snd_soc_component *component;
 	struct snd_soc_dai *dai;
@@ -390,20 +379,9 @@ static int dai_list_seq_show(struct seq_file *m, void *v)
 
 	return 0;
 }
+DEFINE_SHOW_ATTRIBUTE(dai_list);
 
-static int dai_list_seq_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, dai_list_seq_show, NULL);
-}
-
-static const struct file_operations dai_list_fops = {
-	.open = dai_list_seq_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
-
-static int platform_list_seq_show(struct seq_file *m, void *v)
+static int platform_list_show(struct seq_file *m, void *v)
 {
 	struct snd_soc_platform *platform;
 
@@ -416,18 +394,7 @@ static int platform_list_seq_show(struct seq_file *m, void *v)
 
 	return 0;
 }
-
-static int platform_list_seq_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, platform_list_seq_show, NULL);
-}
-
-static const struct file_operations platform_list_fops = {
-	.open = platform_list_seq_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(platform_list);
 
 static void soc_init_card_debugfs(struct snd_soc_card *card)
 {