intel/fs: Work around dual-source blending hangs in combination with SIMD16
It was found that dual-source blending hangs with SIMD16 dispatch in some specific but unknown situation. Which in the wild happen when rgba anti-aliasing is enabled for fonts. Cc: <mesa-stable@lists.freedesktop.org> Closes: mesa/mesa#2183 Signed-off-by:Danylo Piliaiev <danylo.piliaiev@globallogic.com> Reviewed-by:
Lionel Landwerlin <lionel.g.landwerlin@intel.com> Part-of: <mesa/mesa!5037> (cherry picked from commit 296c04d7)