Draft: radv: add has_raytracing flag to radeon_info

Determine whether the device has hardware raytracing support early, and then use this result where needed.

This is a prerequisite for CYAN_SKILLFISH chip enablement. It's still GFX10, not GFX10_3, but has support for image_bvh{,64}_intersect_ray instructions. Just checking for gfx_level is insufficient for it.