drm/stm: Use GEM DMA fbdev emulation

Use the fbdev emulation that is optimized for DMA helpers. Avoids
possible shadow buffering and makes the code simpler.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230313155138.20584-16-tzimmermann@suse.de

drivers/gpu/drm/stm/drv.c

@@ -18,7 +18,7 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
-#include <drm/drm_fbdev_generic.h>
+#include <drm/drm_fbdev_dma.h>
 #include <drm/drm_gem_dma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_module.h>
@@ -203,7 +203,7 @@ static int stm_drm_platform_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_put;
 
-	drm_fbdev_generic_setup(ddev, 16);
+	drm_fbdev_dma_setup(ddev, 16);
 
 	return 0;