iris: only set point sprite overrides if actually using points

Fixes black screen in some FNA games.

Cc: <mesa-stable@lists.freedesktop.org>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3431
Signed-off-by: Yevhenii Kolesnikov <yevhenii.kolesnikov@globallogic.com>
Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7218>
(cherry picked from commit 0c08a66ce526913ed2691f982f600285206248b8)
2 files changed