compiler/nir: rewrite lower_fragcoord_wtrans to use nir_lower_instructions

This compacts the code and makes it easier to extend.

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Andreas Baierl <ichgeh@imkreisrum.de>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6220>
2 files changed