smb: client: default to nonativesocket under POSIX mounts

SMB3.1.1 POSIX mounts require sockets to be created with NFS reparse
points.

Cc: linux-cifs@vger.kernel.org
Cc: Ralph Boehme <slow@samba.org>
Cc: David Howells <dhowells@redhat.com>
Cc: <stable@vger.kernel.org>
Reported-by: Matthew Richardson <m.richardson@ed.ac.uk>
Closes: https://marc.info/?i=1124e7cd-6a46-40a6-9f44-b7664a66654b@ed.ac.uk


Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Steve French <stfrench@microsoft.com>