mlx5dv_devx_alloc_uar(3) on Linux

The text 58c5bbbd40a7, as Debian 10 (Buster) shipped it.

Allocates a DEVX UAR mlx5dv_devx_free_uar - Frees a DEVX UAR

mlx5dv_devx_alloc_uar(3) on Linux now