[PATCH] r8169: ethtool message level control support

Also:
- ratelimit the too much work at interrupt message, so if under massive
  packet load the console doesn't get flooded;
- removal of a few PFX used in contexts where dev->name is available;
- s/->slot_name/pci_name/;
- printed_version is redundant with the debug option. Remove it and let
  the user decide.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>