RDMA/mlx5: Clean UMR QP type flow from mlx5_ib_post_send()

No internal UMR operation is using mlx5_ib_post_send(), remove the UMR QP
type logic from this function.

Link: https://lore.kernel.org/r/0b2f368f14bc9266ebdf92a601ca4e1e5b1e1188.1649747695.git.leonro@nvidia.com


Signed-off-by: Aharon Landau <aharonl@nvidia.com>
Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>