drm/tiny/cirrus: 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>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240419083331.7761-15-tzimmermann@suse.de

drivers/gpu/drm/tiny/cirrus.c

@@ -31,7 +31,7 @@
 #include <drm/drm_damage_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_edid.h>
-#include <drm/drm_fbdev_generic.h>
+#include <drm/drm_fbdev_shmem.h>
 #include <drm/drm_file.h>
 #include <drm/drm_format_helper.h>
 #include <drm/drm_fourcc.h>
@@ -716,7 +716,7 @@ static int cirrus_pci_probe(struct pci_dev *pdev,
 	if (ret)
 		return ret;
 
-	drm_fbdev_generic_setup(dev, 16);
+	drm_fbdev_shmem_setup(dev, 16);
 	return 0;
 }