panfrost: Rename encoder/ to lib/

We'll want both encoding and decoding here, as a generic hardware
interface library based on GenXML.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6196>
28 files changed