We use struct mlx4_buf for kernel QP, CQ and SRQ buffers, and the code
to look up an entry is duplicated in get_cqe_from_buf() and the QP and
SRQ versions of get_wqe(). Factor this out into mlx4_buf_offset().
This will also make it easier to switch over to using vmap() for buffers.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
1c69fc2a90