MTRR use in drivers

[H. Peter Anvin]

An awful lot of drivers, mostly DRI drivers, are still mucking with
MTRRs directly as opposed to using ioremap_wc() or similar interfaces.
In addition to the architecture dependency, this is really undesirable
because MTRRs are a limited resource, whereas page table attributes are not.

Furthermore, this perpetuates the need for the horrific hack known as
"MTRR cleanup".

What, if anything, can we do to clean up this mess?

	-hpa