[ES40-developers] Patch: fix ide controller

[Brian W. <bdw...@in...>]

This patch fixes two things:
1) clears the busmaster active bit when the bit 1 is written to the
busmaster status register.
2) Attempts to refire the interrupt if the controller seems to have
missed it -- before the OS declares a timeout.

This patch fixes the vms boot problems from ide cdrom and it also
allowed me to install tru64 -- albeit with timeouts.

The timeout refire code isn't very well tested, since it is very timing
dependent, and if you have IDE debugging turned on, es40 waits for a
keypress before re-issuing the interrupt (since I want to see what it is
doing)

Brian