smb: server: make use of smbdirect_connection_recvmsg()

smb: server: make use of smbdirect_connection_recvmsg()

This is basically the same logic, it just operates on iov_iter_kvec()
instead of a raw buffer pointer. This allows us to use common
code between client and server.

We keep returning -EINTR instead of -ERESTARTSYS if
wait_event_interruptible() fails. I don't if this is
required, but changing it is a task for another patch.

Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.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>