Now that its Gallium dependencies have been resolved, we can move this
all out to root. The only nontrivial change here is keeping the
pandecode calls in Gallium-panfrost to avoid creating a circular
dependency between encoder/decoder. This could be solved with a third
drm folder but this seems less intrusive for now and Roman would
probably appreciate if I went longer than 8 hours without breaking the
Android build.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <mesa!4382>