pci: distinguish between legitimate failures and non-fatal errors

pci: distinguish between legitimate failures and non-fatal errors

Currently, EAL does not distinguish between actual failures and expected
initialization errors. E.g. sometimes the driver fails to initialize
because it was not supposed to be initialized in the first place, such
as device not being managed by said driver.

This patch makes EAL fail on actual initialization errors while still
skipping over expected initialization errors.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Tested-by: Waterman Cao <waterman.cao@intel.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>