net/mlx5: allow multiple probing for representor

net/mlx5: allow multiple probing for representor

Implement probing of a rte device multiple times, see [1].
Set PCI driver RTE_PCI_DRV_PROBE_AGAIN flag to enable multiple probing
of the PCI device by the PCI common driver.
Consecutive probing requests with a devargs string may contain
repetitive master and representors devices for which eth device should
be created only once. In case an eth device already exists - silently
ignore it.

[1]
commit e9d159c3d534 ("eal: allow probing a device again")

Signed-off-by: Ophir Munk <ophirmu@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>