Fault injection test reported memory leak of hci device as follows:

unreferenced object 0xffff88800b858000 (size 8192):
  comm "kworker/0:2", pid 167, jiffies 4294955747 (age 557.148s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
  backtrace:
    [<0000000070eb1059>] kmem_cache_alloc_trace mm/slub.c:3208
    [<00000000015eb521>] hci_alloc_dev_priv include/linux/slab.h:591
    [<00000000dcfc1e21>] bpa10x_probe include/net/bluetooth/hci_core.h:1240
    [<000000005d3028c7>] usb_probe_interface drivers/usb/core/driver.c:397
    [<00000000cbac9243>] really_probe drivers/base/dd.c:517
    [<0000000024cab3f0>] __driver_probe_device drivers/base/dd.c:751
    [<00000000202135cb>] driver_probe_device drivers/base/dd.c:782
    [<000000000761f2bc>] __device_attach_driver drivers/base/dd.c:899
    [<00000000f7d63134>] bus_for_each_drv drivers/base/bus.c:427
    [<00000000c9551f0b>] __device_attach drivers/base/dd.c:971
    [<000000007f79bd16>] bus_probe_device drivers/base/bus.c:487
    [<000000007bb8b95a>] device_add drivers/base/core.c:3364
    [<000000009564d9ea>] usb_set_configuration drivers/usb/core/message.c:2171
    [<00000000e4657087>] usb_generic_driver_probe drivers/usb/core/generic.c:239
    [<0000000071ede518>] usb_probe_device drivers/usb/core/driver.c:294
    [<00000000cbac9243>] really_probe drivers/base/dd.c:517

hci_alloc_dev() do not init the device's flag. And hci_free_dev()
using put_device() to free the memory allocated for this device,
but it calls just put_device(dev) only in case of HCI_UNREGISTER
flag is set, So any error handing before hci_register_dev() success
will cause memory leak.

To avoid this behaviour we can using kfree() to release dev before
hci_register_dev() success.
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>