nir: account for point-coord origin when lowering it

nir: account for point-coord origin when lowering it

The resulting point-coord origin not only depends on whether
the draw buffer is flipped but also on GL_POINT_SPRITE_COORD_ORIGIN
state. Which makes its transform differ from a transform of wpos.

On freedreno fixes:
 gl-3.2-pointsprite-origin
 gl-3.2-pointsprite-origin -fbo

Fixes: d934d320 "nir: Add flipping of gl_PointCoord.y in nir_lower_wpos_ytransform."
Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Acked-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Jose Maria Casanova Crespo <jmcasanova@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8200>