net/mlx4: optimize stack memory size in probe

net/mlx4: optimize stack memory size in probe

The mlx4_pci_probe function sets a pointer to the mlx4_priv structure,
and during that function fills its fields one by one with relevant
values.

It wants to put a value in the intr_handle field that has all its fields
zero except 2. To do so, it initializes a local struct rte_intr_handle
type variable and updates it only 2 fields and assigns it into the
appropriate field. However, it initializes a very large structure on the
stack while not at all certain that this place exists and in any case it
is very wasteful.

Reset all fields directly to the pointer by memset, then format the 2
fields to the relevant values.

Fixes: 63c2f23c852a ("net/mlx4: use a single interrupt handle")
Cc: stable@dpdk.org
Signed-off-by: Michael Baum <michaelba@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>