Pull up the following revisions, requested by msaitoh in ticket #1329:

sys/dev/pci/if_etreg.h 1.2-1.3
sys/dev/pci/if_et.c 1.23,1.25 and 1.26
via patch

Make et(4) work:
- Add missing ifioctl_common() for SIOCSIFFLAGS to make if_flags
  controllable.
- Enabling TX/RX in et_init() will always fail when cable is not
  plugged in. If this happens, we delay TX/RX enablement until link is
  up.
- Modify flow control stuff a little. It still doesn't work.
- Avoid undefined behavior when reset the chip.
- Code cleanup.

(martin)