- Don't use the status block's link state change bit to micro-optimize

- Don't use the status block's link state change bit to micro-optimize
  performance, instead, read MAC_STS which always contains the correct
  value about link state changing.  Enormous amount of superflucious
  link up events, which keep coming originally when the interface is
  brought up before cable is plugged in, disappear after this change.
- Nuke the no longer needed PCI bridge cache flush.
- Minor style change.