make /dev/pci really readable

[Doug Ambrisko]

Scott Long writes:
| You should not always assume that reading PCI registers has no
| side-effects.  It is certainly legal and possible for a PCI device to
| detect the read request and alter the contents of the register (or some
| other register) as a side effect, or change an internal state machine.
| 'Fixing' the various bits to allow unpriviledged access to 'pciconf -r'
| is dangerous since you would have to teach the system about every pci
| device in existance and how to trap on registers that have side-effects.

I seem to recall reading some PCI chip spec. for a chip I was working on
that did a reset on read of that register.  I can't recall which or where 
so don't take this as fact but a distant memory.

Doug A.