[Nouveau] NVA3: Small misc mem reclocking fixes

[Roy Spliet]

Patch 1 fixes nva3 bailing due to not finding the right ramcfg
Patch 2 is a resend rebased on 3.17.0-rc4 for setting the vblank period
Patch 3-5 handle writes to per-partition registers, for which NVA3 does not
have special broadcast regs available.
Patch 6 removes local structs from NVA3 reclocking in favour of the already
existing "ram->base." variables, like in NVE0

As always, please review and merge when no objections! :-)
Thanks,

Roy