evergreen acceleration support

[Alex Deucher]

I've just pushed out the initial evergreen (radeon HD5xxx)
acceleration support for EXA and Xv to the evergreen_accel branch of
xf86-video-ati.  Full support for EXA and Xv is available.  To use it,
you'll need 2.6.35 with kms enabled.  There are still some GPU hangs
in some cases that we haven't sorted out yet.  Richard will be pushing
out mesa support as soon as he finishes rebasing his tree against mesa
master.  We'll be releasing updated register specs eventually, but as
you can see, most of the registers and bit fields are the same as
r6xx/r7xx.  Happy Hacking!

Alex