Back-merge from drm-fixes into drm-intel-next to sort out two things:

- interlaced support: -fixes contains a bugfix to correctly clear
  interlaced configuration bits in case the bios sets up an interlaced
  mode and we want to set up the progressive mode (current kernels
  don't support interlaced). The actual feature work to support
  interlaced depends upon (and conflicts with) this bugfix.

- forcewake voodoo to workaround missed IRQ issues: -fixes only enabled
  this for ivybridge, but some recent bug reports indicate that we
  need this on Sandybridge, too. But in a slightly different flavour
  and with other fixes and reworks on top. Additionally there are some
  forcewake cleanup patches heading to -next that would conflict with
  currrent -fixes.
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>