RDMA/mlx5: Add support for TLP VAR allocation

RDMA/mlx5: Add support for TLP VAR allocation

Extend the VAR allocation UAPI to accept an optional flags attribute,
allowing userspace to request TLP VAR allocation via the
MLX5_IB_UAPI_VAR_ALLOC_FLAG_TLP flag.

When the TLP flag "MLX5_IB_UAPI_VAR_ALLOC_FLAG_TLP" is specified,
the driver selects the TLP VAR region for allocation instead of the
regular VirtIO VAR region.

Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>