pan/midgard: Hoist temporary coordinate for cubemaps

We'll reuse some of this code for shadow samplers, which are represented
by a distinct source in NIR.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3125>
1 file changed