RDMA/cxgb3: Return correct max_inline_data when creating a QP

Set cap.max_inline_data to the actual max inline data that the adapter
support, so that userspace apps see the right value returned.

Signed-off-by: Jon Mason <jon@opengridcomputing.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>