smb: client: make use of smbdirect_connection_{alloc,free}_send_io()

smb: client: make use of smbdirect_connection_{alloc,free}_send_io()

This simplifies the code and allows us to share more code in common
with the server.

The only difference is that we use ib_dma_unmap_page() for all sges,
this simplifies the logic and doesn't matter as
ib_dma_unmap_single() and ib_dma_unmap_page() both operate
on dma_addr_t and dma_unmap_single_attrs() is just an
alias for dma_unmap_page_attrs().

We already had such an inconsistency before
as we called ib_dma_unmap_single(), while we mapped
using ib_dma_map_page() in smb_set_sge().

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>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>