RDMA/rxe: Move AV from rxe_send_wqe to rxe_send_wr

RDMA/rxe: Move AV from rxe_send_wqe to rxe_send_wr

Move the struct rxe_av av from struct rxe_send_wqe to struct rxe_send_wr
placing it in wr.ud at the same offset as it was previously. This has the
effect of increasing the size of struct rxe_send_wr while keeping the size
of struct rxe_send_wqe the same. This better reflects the use of this
field which is only used for UD sends. This change has no effect on ABI
compatibility so the modified rxe driver will operate with older versions
of rdma-core.

Link: https://lore.kernel.org/r/20211007204051.10086-2-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>