radv: force enable VK_AMD_shader_ballot for Wolfenstein Youngblood

This gives a nice boost, +20% at this time on my Vega 56. Shader
ballot should be enabled by default at some point but it reduces
performance a bit (-6%) with Wolfeinstein II. Enable it only for
Youngblood at the moment, like what we did for Talos in the past.

As a bonus point, it gets rid of some minor artifacts that only
happens when ballot is disabled for some reasons.

Cc: 19.2 <mesa-stable@lists.freedesktop.org
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit a6ad9e8c)