drm/sti: 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 <[e-mail]>
Reviewed-by: Javier Martinez Canillas <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/sti/sti_drv.c

···
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_debugfs.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_of.h>
···
 
 	drm_mode_config_reset(ddev);
 
-	drm_fbdev_generic_setup(ddev, 32);
+	drm_fbdev_dma_setup(ddev, 32);
 
 	return 0;