memory: emif: Convert to DEFINE_SHOW_ATTRIBUTE

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Along with this change, we get additionally:
        .owner          = THIS_MODULE,
        .llseek         = seq_lseek,

1. The llseek method is used to change the current read/write position
in a file which can be ignored if you don't use it.
2. The owner is not even a method. Instead, it is a pointer to the
module that “owns” this structure; it is used by the kernel to maintain
the module's usage count which can be ignored.

Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Link: https://lore.kernel.org/r/20200917125113.103550-1-miaoqinglang@huawei.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

drivers/memory/emif.c

@@ -131,16 +131,7 @@ static int emif_regdump_show(struct seq_file *s, void *unused)
 	return 0;
 }
 
-static int emif_regdump_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, emif_regdump_show, inode->i_private);
-}
-
-static const struct file_operations emif_regdump_fops = {
-	.open			= emif_regdump_open,
-	.read			= seq_read,
-	.release		= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(emif_regdump);
 
 static int emif_mr4_show(struct seq_file *s, void *unused)
 {
@@ -150,16 +141,7 @@ static int emif_mr4_show(struct seq_file *s, void *unused)
 	return 0;
 }
 
-static int emif_mr4_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, emif_mr4_show, inode->i_private);
-}
-
-static const struct file_operations emif_mr4_fops = {
-	.open			= emif_mr4_open,
-	.read			= seq_read,
-	.release		= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(emif_mr4);
 
 static int __init_or_module emif_debugfs_init(struct emif_data *emif)
 {