radv: disable VRS entirely on GFX11

radv: disable VRS entirely on GFX11

Based on registers, VRS changed a lot and it's unclear how to program
it. This disable VK_KHR_fragment_shading_rate, VRS flat shading and
RADV_FORCE_VRS.

Cc: 22.3 mesa-stable
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20054>
(cherry picked from commit 80072df8246f580a4c7d31fb82a9f746c3e1ba8d)