fb/ramnva3: WIP NVA8 link training unit

XXX: What ram types, chips use this?
fb/ramnva3: Use ram->base structs instead of local structs

This will ease the use of generic timing and MR generation bits later
fb/ramnva3: Ressurect timing calculation code
fb/nva3: WIP Start on some reclocking bits
fb/sddr3: WIP Expand MR generation with various bits
pwr/memx: WIP Wait for VBLANK if desired
WIP train external hook