Revert "Bluetooth: hci_core: Fix build warnings"

This reverts commit 194ab82c1e which is
commit dcda165706b9fbfd685898d46a6749d7d397e0c0 upstream.

It breaks the android ABI and if this is needed in the future, can be
brought back in an abi-safe way.

Bug: 161946584
Change-Id: I4a64dca20bcdfe9cbe33fc23c7d3d1b252f4b873
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

include/net/bluetooth/hci_core.h

@@ -209,7 +209,7 @@ struct hci_dev {
 	struct list_head list;
 	struct mutex	lock;
 
-	const char	*name;
+	char		name[8];
 	unsigned long	flags;
 	__u16		id;
 	__u8		bus;

net/bluetooth/hci_core.c

@@ -3193,11 +3193,7 @@ int hci_register_dev(struct hci_dev *hdev)
 	if (id < 0)
 		return id;
 
-	error = dev_set_name(&hdev->dev, "hci%u", id);
-	if (error)
-		return error;
-
-	hdev->name = dev_name(&hdev->dev);
+	snprintf(hdev->name, sizeof(hdev->name), "hci%d", id);
 	hdev->id = id;
 
 	BT_DBG("%p name %s bus %d", hdev, hdev->name, hdev->bus);
@@ -3219,6 +3215,8 @@ int hci_register_dev(struct hci_dev *hdev)
 	if (!IS_ERR_OR_NULL(bt_debugfs))
 		hdev->debugfs = debugfs_create_dir(hdev->name, bt_debugfs);
 
+	dev_set_name(&hdev->dev, "%s", hdev->name);
+
 	error = device_add(&hdev->dev);
 	if (error < 0)
 		goto err_wqueue;