v3d/compiler: implement load interpolated input intrinsics

We will lower GLSL interpolateAt functions to these.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Acked-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7155>
1 file changed