[Intel-gfx] [rfc] start slimming down intel_display.c

[Dave Airlie]

Recent events led me to notice a 20k loc file that seems excessive.

If a new driver came along and asked to merge this monster I'd say no,
so why has the in tree code gotten this bad. Standards are clearly
not being kept once code is merged, which doesn't bode well for the
future.

Anyways, as an effort to kick start some cleaning, I've refactored
a few thousand lines of code out of this into separate files, I've
been pretty arbitary and I'm sure there are many nicers ways to slice
this, but this is my effort.

Dave.