common/mlx5: fix aligned malloc

common/mlx5: fix aligned malloc

Before this commit system call memalign was used for aligned
allocations, however memalign is deprecated.

Based on (1) - POSIX requires that memory aligned allocations can be
freed using free. Some systems provide no way to reclaim memory
allocated with memalign (because one can only pass to free a pointer
gotten from malloc, while, memalign would call malloc and then align the
obtained value).
Another issue is that 64/32 bits architectures use a minimal alignment
size. So any requested alignment below the minimal system size can be
simplified by calling malloc.

The glibc implementation allows memory obtained from posix_memalign to
be reclaimed with free.  This commit replaces system call memalign with
system call posix_memalign. It also calls malloc in case the requested
alignment is below the minimal system size.

(1) https://linux.die.net/man/3/memalign

Fixes: d38e3d526657 ("common/mlx5: add memory management functions")
Cc: stable@dpdk.org
Signed-off-by: Ophir Munk <ophirmu@nvidia.com>
Acked-by: Matan Azrad <matan@mellanox.com>