cifs: Fix a debug message

This debug message was never shown because it was checking for NULL
returns but extract_hostname() returns error pointers.

Fixes: 93d5cb51 ("cifs: Add support for failover in cifs_reconnect()")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Paulo Alcantara <palcantara@suse.de>