Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

On certain boards, there's BIOS scripts and memory timings that need to
be modified with the memclk.  Just pass in the entire perflvl struct and
let the chipset-specific code decide what to do.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

Guarded by a module parameter for the moment, read the code for the
magic value which enables it.
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

This will make nouveau_pm attempt to report the card's current performance
level both during bootup, and through sysfs.

This is a very initial implementation, and can be improved a *lot*
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>