pan/bi: Merge BIR_INDEX_FAU and BIR_INDEX_BLEND

There's no reason to separate these, and it's more convenient not to.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8215>
4 files changed