drm/udl: Use drmm_add_final_kfree

With this we can drop the final kfree from the release function.

v2: We need drm_dev_put to unroll the driver creation (once
drm_dev_init and drmm_add_final_kfree suceeded), otherwise
the drmm_ magic doesn't happen.

v3: Actually squash in the fixup (Laurent).
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200323144950.3018436-7-daniel.vetter@ffwll.ch

drivers/gpu/drm/udl/udl_drv.c

@@ -10,6 +10,7 @@
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_file.h>
 #include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_managed.h>
 #include <drm/drm_ioctl.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_print.h>
@@ -38,7 +39,6 @@ static void udl_driver_release(struct drm_device *dev)
 	udl_fini(dev);
 	udl_modeset_cleanup(dev);
 	drm_dev_fini(dev);
-	kfree(dev);
 }
 
 static struct drm_driver driver = {
@@ -77,11 +77,11 @@ static struct udl_device *udl_driver_create(struct usb_interface *interface)
 
 	udl->udev = udev;
 	udl->drm.dev_private = udl;
+	drmm_add_final_kfree(&udl->drm, udl);
 
 	r = udl_init(udl);
 	if (r) {
-		drm_dev_fini(&udl->drm);
-		kfree(udl);
+		drm_dev_put(&udl->drm);
 		return ERR_PTR(r);
 	}