Bluetooth: Refactor read_ext_controller_info handler

static int read_ext_controller_info(struct sock *sk, struct hci_dev *hdev,

				    void *data, u16 data_len)

{

	struct mgmt_rp_read_ext_info *rp;

	char buff[512];

	char buf[512];

	struct mgmt_rp_read_ext_info *rp = (void *)buf;

	u16 eir_len = 0;

	u8 name_len;

	size_t name_len;

	BT_DBG("sock %p %s", sk, hdev->name);

	memset(&buf, 0, sizeof(buf));

	hci_dev_lock(hdev);

	bacpy(&rp->bdaddr, &hdev->bdaddr);

	rp->version = hdev->hci_ver;

	rp->manufacturer = cpu_to_le16(hdev->manufacturer);

	rp->supported_settings = cpu_to_le32(get_supported_settings(hdev));

	rp->current_settings = cpu_to_le32(get_current_settings(hdev));

	if (hci_dev_test_flag(hdev, HCI_BREDR_ENABLED))

		eir_len = eir_append_data(buff, eir_len,

					  EIR_CLASS_OF_DEV,

		eir_len = eir_append_data(rp->eir, eir_len, EIR_CLASS_OF_DEV,

					  hdev->dev_class, 3);

	name_len = strlen(hdev->dev_name);

	eir_len = eir_append_data(buff, eir_len, EIR_NAME_COMPLETE,

	eir_len = eir_append_data(rp->eir, eir_len, EIR_NAME_COMPLETE,

				  hdev->dev_name, name_len);

	name_len = strlen(hdev->short_name);

	eir_len = eir_append_data(buff, eir_len, EIR_NAME_SHORT,

	eir_len = eir_append_data(rp->eir, eir_len, EIR_NAME_SHORT,

				  hdev->short_name, name_len);

	rp = kzalloc(sizeof(*rp) + eir_len, GFP_KERNEL);

	if (!rp)

		return -ENOMEM;

	rp->eir_len = cpu_to_le16(eir_len);

	memcpy(rp->eir, buff, eir_len);

	bacpy(&rp->bdaddr, &hdev->bdaddr);

	rp->version = hdev->hci_ver;

	rp->manufacturer = cpu_to_le16(hdev->manufacturer);

	rp->supported_settings = cpu_to_le32(get_supported_settings(hdev));

	rp->current_settings = cpu_to_le32(get_current_settings(hdev));

	hci_dev_unlock(hdev);