radv: Write correct dispatch size for RGP.

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6875>
diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
index 70f9bea..4a302ba 100644
--- a/src/amd/vulkan/radv_cmd_buffer.c
+++ b/src/amd/vulkan/radv_cmd_buffer.c
@@ -5524,7 +5524,8 @@
 	struct radeon_cmdbuf *cs = cmd_buffer->cs;
 	struct radv_userdata_info *loc;
 
-	radv_describe_dispatch(cmd_buffer, 8, 8, 8);
+	radv_describe_dispatch(cmd_buffer, info->blocks[0], info->blocks[1],
+	                       info->blocks[2]);
 
 	loc = radv_lookup_user_sgpr(pipeline, MESA_SHADER_COMPUTE,
 				    AC_UD_CS_GRID_SIZE);