lib/pci: reduce library noise

Avoid printfs in library code unless in a printing function, e.g.
pci_dev_print. Particularly we can avoid printing anything the
caller can easily print themselves, if so desired.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>