net/mlx5: Allocate root ns memory using kzalloc to match kfree
root ns is yet another fs core node which is freed using kfree() by
tree_put_node().
Rest of the other fs core objects are also allocated using kmalloc
variants.
However, root ns memory is allocated using kvzalloc().
Hence allocate root ns memory using kzalloc().
Fixes: 7c70b5933b357 ("net/mlx5_core: Flow steering tree initialization") Signed-off-by: Parav Pandit <parav@mellanox.com> Reviewed-by: Daniel Jurgens <danielj@mellanox.com> Reviewed-by: Mark Bloch <markb@mellanox.com> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>