Bluetooth: 6lowpan: Fix debugfs_simple_attr.cocci warnings

Use DEFINE_DEBUGFS_ATTRIBUTE rather than DEFINE_SIMPLE_ATTRIBUTE
for debugfs files.

Semantic patch information:
Rationale: DEFINE_SIMPLE_ATTRIBUTE + debugfs_create_file()
imposes some significant overhead as compared to
DEFINE_DEBUGFS_ATTRIBUTE + debugfs_create_file_unsafe().

Generated by: scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/6lowpan.c

@@ -1108,7 +1108,7 @@ static int lowpan_enable_get(void *data, u64 *val)
 	return 0;
 }
 
-DEFINE_SIMPLE_ATTRIBUTE(lowpan_enable_fops, lowpan_enable_get,
+DEFINE_DEBUGFS_ATTRIBUTE(lowpan_enable_fops, lowpan_enable_get,
 			 lowpan_enable_set, "%llu\n");
 
 static ssize_t lowpan_control_write(struct file *fp,
@@ -1278,8 +1278,9 @@ static struct notifier_block bt_6lowpan_dev_notifier = {
 
 static int __init bt_6lowpan_init(void)
 {
-	lowpan_enable_debugfs = debugfs_create_file("6lowpan_enable", 0644,
-						    bt_debugfs, NULL,
+	lowpan_enable_debugfs = debugfs_create_file_unsafe("6lowpan_enable",
+							   0644, bt_debugfs,
+							   NULL,
 							   &lowpan_enable_fops);
 	lowpan_control_debugfs = debugfs_create_file("6lowpan_control", 0644,
 						     bt_debugfs, NULL,