FILO fixups

[Ronald G. Minnich]

I've just finished fixups to filo that make it quite a bit faster. 

First, it used to scan the bus twice, the first time to do a count. That's 
slow, although it was a nice algorithm. But it only needed to find at most 
2 devices. 

Now it scans until the device is found and returns it. Even in the worst
case, the new pci scan is always faster than the old.

There are new options in addition to PCI_BRUTE_SCAN. 

PCI_BRUTE_SCAN means: 
scan everything ...

PCI_BRUTE_SCAN_START

... but start at this bus (VERY good on k8, as the scan of 0:19.* takes 
FOREVER).

PCI_BRUTE_SCAN_LIMIT = 2
... and end here -1(useful when you know that the busses don't range to 
256)

And the 'instant gratification' option:

IDE_HINT_BUS
IDE_HINT_DEV
IDE_HINT_FUNC

All three must be set or not set or you get a compile-time warning. IF all
three are set, FILO will probe the device and IF it is an ide controller
use that. If it's not an ide controller, filo will scan busses as usual.

This last option REALLY speeds things up

ron