radv: only enable VK_AMD_gpu_shader_{half_float,int16} on GFX9+
These two extensions are supported on GFX8 but the throughput of 16-bit floats/integers is same as 32-bit. Also, shaderInt16 is only enabled on GFX9+ for the same reason, be more consistent. This fixes a crash with Wolfenstein II because it expects shaderInt16 to be enabled when VK_AMD_gpu_shader_half_float is exposed. Note that AMDVLK only enables these extensions on GFX9+. Cc: 19.1 <mesa-stable@lists.freedesktop.org> Signed-off-by:Samuel Pitoiset <samuel.pitoiset@gmail.com> Reviewed-by:
Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>