freedreno/ir3: fix rasterflat/glxgears

Ofc legacy gl features that are broken don't trigger fails in deqp.  I
should remember to test glxgears more often.

Fixes: 7ff6705b freedreno/ir3: convert to "new style" frag inputs
Signed-off-by: Rob Clark <robdclark@chromium.org>
(cherry picked from commit 9faf218b)