radv: Expose EXT_hdr_metadata on RADV

This can be unconditionally exposed as it only has an effect on
swapchains with a HDR colorspace, which only is exposed with HDR
capable displays on KHR_display

docs/features.txt

@@ -559,6 +559,7 @@ Khronos extensions that are not part of any Vulkan version:
   VK_EXT_global_priority                                DONE (anv, radv, tu)
   VK_EXT_global_priority_query                          DONE (anv, radv, tu)
   VK_EXT_graphics_pipeline_library                      DONE (lvp)
+  VK_EXT_hdr_metadata                                   DONE (radv)
   VK_EXT_image_2d_view_of_3d                            DONE (anv, radv, tu, lvp)
   VK_EXT_image_drm_format_modifier                      DONE (anv, radv/gfx9+, tu, v3dv, vn)
   VK_EXT_image_view_min_lod                             DONE (anv, radv, tu, vn)

src/amd/vulkan/radv_device.c

@@ -591,6 +591,7 @@ radv_physical_device_get_supported_extensions(const struct radv_physical_device
       .EXT_global_priority_query = true,
       .EXT_graphics_pipeline_library = !device->use_llvm &&
                                        !!(device->instance->perftest_flags & RADV_PERFTEST_GPL),
+      .EXT_hdr_metadata = true,
       .EXT_host_query_reset = true,
       .EXT_image_2d_view_of_3d = true,
       .EXT_image_drm_format_modifier = device->rad_info.gfx_level >= GFX9,