st/glsl_to_tgsi: don't increase immediate index by 1.
Immediates are stored into a separate table, and are consolidated, so if we get an immediate we don't need to offset it as the index it has is correct. Cc: "11.2 12.0" <mesa-stable@lists.freedesktop.org> Signed-off-by:Dave Airlie <airlied@redhat.com> (cherry picked from commit 27d456cc)