dev: fix vdev attach after PCI mismatch

dev: fix vdev attach after PCI mismatch

If the device is a vdev, the parsing for PCI will fail with -EFAULT,
and will not try to check for a vdev.

Checking against error values returned by rte_eal_hotplug_add is
inelegant and prone to mistakes. Additionally, the failed PCI probe
prints a useless error that would throw off unsuspecting users:

   ERROR: failed to parse device "pci:net_ring0"

This error is printed when attempting to probe a virtual device first
with the PCI bus (here, a net_ring0 device).

Use the relevant functions to infer the intended bus. The limitation to
PCI or vdev device is kept for strict API compatibility. Thus the PCI
probe attempt is avoided and the right function is directly called.

Fixes: 1c35f666df07 ("dev: fix attach proceeding with vdev on PCI success")

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>