RDMA/mlx5: Fail early if user tries to create flows on IB representors

IB representors don't support creation of RAW ethernet QP flows.  Disable
them by reusing existing RDMA/core support macros.  We do it for both
creation and matcher because latter is not usable if no flow creation is
available.

Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>