pan/bi: Add preliminary LOAD_UNIFORM implementation

Lots of things are missing (indirect access, UBOs) but we have this
stubbed out for now.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4097>
4 files changed