broadcom/compiler: implement nir_intrinsic_load_sample_pos

This is intended to return the sample location within the pixel.

Fixes:
dEQP-VK.pipeline.multisample_shader_builtin.sample_position.*

Reviewed-by: Alejandro PiƱeiro <apinheiro@igalia.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>
1 file changed