In float pointing rules adding +0.0f preserves all values except
for -0.0f, so what we want here is to add -0.0f. In the future
we should add proper support for float immediates in the assembler.
Fixes: fafdd24285 ("intel/executor: Update bfloat example")
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34105>