MFC: r191076

MFC: r191076

- Remove the second license as I'm also fine with the first one.
- Remove redundant softc members for RIDs.
- Change some softc members to be unsigned where more appropriate.
- Add some missing const.
- Remove support for mmap(2)'ing VGA I/O as it was broken [1] and
  not required by X.Org anyway.
- Fix some confusion between bus, physical and virtual addresses
  which mostly consisted in using members of struct video_adapter
  inappropriately but wasn't fatal except for the regular framebuffer
  mmap(2)'ing.
- Remove redundant bzero(9)'ing of the softc.
- Don't map the framebuffer twice in case the firmware has already
  mapped it as besides wasting resources this isn't possible with
  all MMUs. This is a bit tricky as a) just because the firmware
  provides a property with a virtual address doesn't mean it's
  actually mapped (but typically is when the framebuffer is the
  console) and b) the firmware doesn't necessarily map it with
  the same byteorder as we do. This makes machfb(4) work on machines
  with cheetah-class MMUs (including X.Org).

Reported by:	Michael Plass [1]
Approved by:	re (kib)

git-svn-id: svn://svn.freebsd.org/base/releng/7.2@191231 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f