maintainers: update mlx drivers sub tree
maintainers: update mlx drivers sub tree

Mellanox PMD patches should target the next-net-mlx sub tree.

Signed-off-by: Shahaf Shuler <59427d49da6f2b944fbf4cb5ee70ef3ac25f744f@mellanox.com>
Acked-by: Thomas Monjalon <5f50a84c1fa3bcff146405017f36aec1a10a9e38@monjalon.net>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk