smb: smbdirect: introduce the basic smbdirect.ko

smb: smbdirect: introduce the basic smbdirect.ko

This exports the functions needed by cifs.ko and ksmbd.ko.

It doesn't yet provide a generic socket layer, but it
is a good start to introduce that on top.
It will be much easier after Davids refactoring
using MSG_SPLICE_PAGES, will make it easier to
use the socket layer without an additional copy.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>