panfrost: Inline panfrost_get_default_swizzle

This commit replaces panfrost_get_default_swizzle with an inlined
implementation where the returned values can be determined at compile
time.

According to perf, this previously used about 2% CPU for Openarena.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3824>
5 files changed