sw64: rename debugfs dir sw_64 to sw64

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56OLG

--------------------------------
Signed-off-by: NHe Sheng <hesheng@wxiat.com>
Signed-off-by: NGu Zitao <guzitao@wxiat.com>

arch/sw_64/kernel/setup.c

@@ -976,7 +976,7 @@ static int __init debugfs_sw64(void)
 {
 	struct dentry *d;
 
-	d = debugfs_create_dir("sw_64", NULL);
+	d = debugfs_create_dir("sw64", NULL);
 	if (!d)
 		return -ENOMEM;
 	sw64_debugfs_dir = d;