MFC r207622-207623,207638

MFC r207622-207623,207638
r207622:
  Drop driver lock before exiting from interrupt handler.

r207623:
  Make sure to check whether driver is running before processing
  received frames. Also check driver has valid ifp pointer before
  calling msk_stop() in device_shutdown handler. While I'm here
  remove unnecessary accesses to interrupt mask registers in
  device_shutdown handler because driver puts the controller into
  reset state.
  With these changes, msk(4) now survive from heavy RX traffic(1byte
  UDP frame) while reboot is in progress.

r207638:
  When VLAN hardware tagging is disabled, make sure to disable VLAN
  checksum offloading as well as TSO over VLAN.

git-svn-id: svn://svn.freebsd.org/base/stable/8@207884 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f