Commit 8ae94cafa5 added a DNS resolution
of the `device` part of the volume option.
The previous way to resolve the passed hostname was to use `addr`
option, which was handled by the same code path as the `nfs` mount type.
The issue is that `addr` is also an SMB module option handled by kernel
and passing a hostname as `addr` produces an invalid argument error.
To fix that, restore the old behavior to handle `addr` the same way as
before, and only perform the new DNS resolution of `device` if there is
no `addr` passed.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>