xmlconfig: add kernel_driver device attribute

This attribute can be used by loader to apply different
option to device use specific kernel driver.

Signed-off-by: Qiang Yu <Qiang.Yu@amd.com>
Acked-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/gallium/auxiliary/pipe-loader/pipe_loader.c

@@ -108,7 +108,7 @@ pipe_loader_load_options(struct pipe_loader_device *dev)
 
    driParseOptionInfo(&dev->option_info, xml_options);
    driParseConfigFiles(&dev->option_cache, &dev->option_info, 0,
-                       dev->driver_name);
+                       dev->driver_name, NULL);
 }
 
 char *