drm/nouveau/bios: Add parsing of VPSTATE table

This table contains three important clocks:

base  clock: This is the non boosted max clock.
tdp   clock: The clock at wich the vbios guarentees the TDP won't ever be
             exceeded at max load (seems to be always the same as the base
             clock, but behaves differently).
boost clock: The avg clock the gpu will stay boosted to. It doesn't seem to
             affect the behaviour of the nvidia driver at all though.

v2: Make clear that base/boost/tdp fields are ids.
v5: Rename Base clock to vpstate.
    Make vbios pointers 32bit.

Signed-off-by: Karol Herbst <karolherbst@gmail.com>
Reviewed-by: Martin Peres <martin.peres@free.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>