drm/radeon/kms: Fix device tree linkage of DP i2c buses too

Properly set the parent device of DP i2c buses before registering them
too.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_i2c.c

@@ -958,6 +958,7 @@ struct radeon_i2c_chan *radeon_i2c_create_dp(struct drm_device *dev,
 	i2c->rec = *rec;
 	i2c->adapter.owner = THIS_MODULE;
 	i2c->adapter.class = I2C_CLASS_DDC;
+	i2c->adapter.dev.parent = &dev->pdev->dev;
 	i2c->dev = dev;
 	snprintf(i2c->adapter.name, sizeof(i2c->adapter.name),
 		 "Radeon aux bus %s", name);