smb: client: let smbd_post_send_negotiate_req() use smbd_post_send()

smb: client: let smbd_post_send_negotiate_req() use smbd_post_send()

The server has similar logic and it makes sure that
request->wr is used instead of a stack struct ib_send_wr send_wr.

This makes sure send_done can see request->wr.send_flags
as the next commit will check for IB_SEND_SIGNALED

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>