smb: client: introduce and use smbd_{alloc, free}_send_io()

smb: client: introduce and use smbd_{alloc, free}_send_io()

This is basically a copy of smb_direct_{alloc,free}_sendmsg()
in the server, with just using ib_dma_unmap_page() in all
cases, which is the same as ib_dma_unmap_single().

We'll use this logic in common code in future.
(I basically backported it from my branch that
as already has everything in common).

Cc: <stable@vger.kernel.org> # 6.18.x
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: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>