commit d9319560 upstream.

If we fail to find a hci device pointer in hci_uart, don't try
to deref the NULL one we do have.
Signed-off-by: Jun Nie <njun@marvell.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Willy Tarreau <w@1wt.eu>