freedreno/ir3: inline const emit

freedreno/ir3: inline const emit

Drop vfunc callbacks for per-gen packet emit, and instead have a header
that is #include'd once per gen.

We'll end up with multiple copies of some of this, but since we never
have multiple gen's of adreno on a single device, only one copy will be
paged in (and hopefully in the I-cache for hot-paths)

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4813>