RADV Enables Vulkan Video By Default For RDNA3 / VCN4 GPUs

With Mesa's RADV driver supporting Vulkan Video for accelerated video encode/decode using this cross-platform, industry standard API it hasn't been exposed by default for RDNA3 graphics processors bearing VCN4 IP. That has now changed for Mesa 24.3 when using the latest VCN4 firmware...