some minor dal cleanups and example of future patches

[Dave Airlie]

So whenever I look at DAL I find myself trying to figure out what
all of it does, and this leads me to deleting things, so I'm just
sending out some stuff that I cleaned today.

One thing I noticed in passing is the displayport code seems
possibly endian unsafe, it casts bytes read from hardware into
bitfields, this is the best defined behaviour and is generally
a pattern we try to steer away from.

The porting the displayport code to use drm defines is the
sort of example of a cleanup patch that might cause problems
for you in code sharing, but is the exact sort of patch that
has been applied to other drivers in the past.

Dave.