cifs: change cifs_call_async to use smb_rqst structs

For now, none of the callers populate rq_pages. That will be done for
writes in a later patch. While we're at it, change the prototype of
setup_async_request not to need a return pointer argument. Just
return the pointer to the mid_q_entry or an ERR_PTR.

Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --cc fs/cifs/cifsglob.h
Simple merge

diff --cc fs/cifs/cifsproto.h
Simple merge

diff --cc fs/cifs/cifssmb.c
Simple merge

diff --cc fs/cifs/smb2pdu.c
Simple merge

diff --cc fs/cifs/smb2proto.h
Simple merge

diff --cc fs/cifs/smb2transport.c
Simple merge

diff --cc fs/cifs/transport.c
Simple merge