fbdev: Add Kconfig macro FB_IOMEM_HELPERS_DEFERRED

The new Kconfig macro FB_IOMEM_HELPERS_DEFERRED selects fbdev's
helpers for device I/O memory and deferred I/O. Drivers should
use it if they perform damage updates on device I/O memory.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230828132131.29295-4-tzimmermann@suse.de

drivers/video/fbdev/core/Kconfig

@@ -151,6 +151,12 @@ config FB_IOMEM_HELPERS
 	select FB_CFB_FILLRECT
 	select FB_CFB_IMAGEBLIT
 
+config FB_IOMEM_HELPERS_DEFERRED
+	bool
+	depends on FB_CORE
+	select FB_DEFERRED_IO
+	select FB_IOMEM_HELPERS
+
 config FB_SYSMEM_HELPERS
 	bool
 	depends on FB_CORE