Bluetooth: Fix return value in hci_dev_do_close()

hci_error_reset() return without calling hci_dev_do_open() when
hci_dev_do_close() return error value which is not 0.

Also, hci_dev_close() return hci_dev_do_close() function's return
value.

But, hci_dev_do_close() return always 0 even if hdev->shutdown
return error value. So, fix hci_dev_do_close() to save and return
the return value of the hdev->shutdown when it is called.

Signed-off-by: Kangmin Park <l4stpr0gr4m@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>