eal: fix positive error codes from probe/remove

eal: fix positive error codes from probe/remove

According to API, 'rte_dev_probe()' and 'rte_dev_remove()' must
return 0 or negative error code. Bus code returns positive values
if device wasn't recognized by any driver, so the result of
'bus->plug/unplug()' must be converted. 'local_dev_probe()' and
'local_dev_remove()' also has their internal API, so the conversion
should be done there.

Positive on remove means that device not found by driver.
Positive on probe means that there are no suitable buses/drivers,
i.e. device is not supported.

Users of these API fixed to provide a good example by respecting
DPDK API. This also will allow to catch such issues in the future.

Fixes: a3ee360f4440 ("eal: add hotplug add/remove device")
Fixes: 244d5130719c ("eal: enable hotplug on multi-process")
Cc: stable@dpdk.org
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>