2nd round of stuff for 4.11:

- DP link rate fixes (DK)
- prep work for atomic wm updates on vlv/chv (Ville)
- platform enumeration cleanup (Jani)
- dsi fixes and cleaups (Hans de Goede)
- gen9 wm fixes (Mahesh Kumar)
- prep work for DP link failure fallback handling (Manasi)
- introduce GEM_WARN_ON (Matthew Auld)
- overlay fixes and cleanups (Ville)
- make is_lp apply to all modern/gen7+ atom-based platforms (Rodrigo)

Tons of small polish, fixes and cleanups all over. This time around
this is about half the patches!