[Nouveau] [RFC] Fermi/Kepler identify DLLoff

[Roy Spliet]

Hello,

Attached a small patch that correctly identifies the DLLoff bit for >=GF100.
Marked RFC because I haven't seen any GDDR5 samples that *enable* the DLL. I'd
like to verify whether the DLL should be reset when enabled. Could increase
likelihood of succesfull reclock.
Ben: could you do some experiments with this bit to see if GDDR5 needs some DLL
reset logic?
Thanks, and happy reviewing!

Roy