sh: fix seq_file memory leak

When using single_open(), single_release() should be used instead
of seq_release(), otherwise there is a memory leak.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/mm/pmb.c b/arch/sh/mm/pmb.c
index 46911bc..cef7276 100644
--- a/arch/sh/mm/pmb.c
+++ b/arch/sh/mm/pmb.c
@@ -385,7 +385,7 @@
 	.open		= pmb_debugfs_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= seq_release,
+	.release	= single_release,
 };
 
 static int __init pmb_debugfs_init(void)