Fix kernel boot issue on cats.

The delay(9) loop, used before the clock device is probed and a hardware timer
is available, was out by a factor of 625.

This wasn't an issue until revision 1.45 of sys/dev/ic/pckbc.c which switched
to using delay(9) when polling the keyboard controller.

Cats attaches the console (and pckbc) before the clock has been probed, and so
the delay loop code is used causing issue with the keyboard polling.

(chris)