panfrost: Rename lower_store to is_blend in pan_lower_framebuffer

The bool will be used for deciding whether to do a per-sample load.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5930>
1 file changed