drm/gud: Use fbdev-shmem

Implement fbdev emulation with fbdev-shmem. Avoids the overhead of
fbdev-generic's additional shadow buffering. No functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240419083331.7761-11-tzimmermann@suse.de

drivers/gpu/drm/gud/gud_drv.c

@@ -18,7 +18,7 @@
 #include <drm/drm_damage_helper.h>
 #include <drm/drm_debugfs.h>
 #include <drm/drm_drv.h>
-#include <drm/drm_fbdev_generic.h>
+#include <drm/drm_fbdev_shmem.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_atomic_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
@@ -622,7 +622,7 @@ static int gud_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
 	drm_kms_helper_poll_init(drm);
 
-	drm_fbdev_generic_setup(drm, 0);
+	drm_fbdev_shmem_setup(drm, 0);
 
 	return 0;
 }