virgl: also remove dimension on indirect.

This fixes some dEQP tests that generated bad shaders.

Fixes: b6f6ead1 (virgl: drop const dimensions on first block.)
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit 49c61d8b)