nir/lower_gs_intrinsics: fix primitive count for points
When primitive is points, EndPrimitive can't be used to count primitive. Need to use vertex count instead. And it's also not needed to do vertex per primitive count and overwrite incomplete primitive work for points. Fixes: 2be99012 ("nir: Add ability to count emitted GS primitives.") Reviewed-by:Timur Kristóf <timur.kristof@gmail.com> Signed-off-by:
Qiang Yu <yuq825@gmail.com> Part-of: <mesa/mesa!17805> (cherry picked from commit 84956286)