net/failsafe: fix PCI devices init

net/failsafe: fix PCI devices init

When trying to attach a port as a sub-device, the ethdev port
was compared with devargs.
In the case of a PCI device, the name in devargs is the PCI address.
And since DPDK 17.08, the devargs name of the underlying device was
used to match an ethdev port:
        a1e7c17555e8 ("ethdev: use device name from device structure")

But the recent commit 72e3efb149cc has reverted this wrong matching
to use the ethdev port name as identifier of the port.
It impacts functions like rte_eth_dev_allocated() used in failsafe
for matching ports with given devargs.
The fix is to search for matching devargs in underlying device of
all ethdev ports.
If many ports match the same PCI device, only the first one is matched.

This limitation was already present in previous implementation of
rte_eth_dev_allocated(), and must be adressed later with a better
devargs syntax.

Fixes: 72e3efb149cc ("ethdev: revert use port name from device structure")
Cc: stable@dpdk.org
Signed-off-by: Raslan Darawsheh <rasland@mellanox.com>
Acked-by: Gaetan Rivet <gaetan.rivet@6wind.com>