fbdev/xen-fbfront: Select FB_SYS_HELPERS_DEFERRED

The Kconfig token FB_SYS_HELPERS_DEFERRED selects everything that
is required for deferred I/O on system-memory framebuffers. Select
it from XEN_FBDEV_FRONTEND in favor of the existing identical selection.

Signed-off-by: Thomas Zimmermann <[email protected]>
Reviewed-by: Sam Ravnborg <[email protected]>
Acked-by: Helge Deller <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: Thomas Zimmermann

drivers/video/fbdev/Kconfig

@@ -2065,11 +2065,7 @@ config FB_VIRTUAL
 config XEN_FBDEV_FRONTEND
 	tristate "Xen virtual frame buffer support"
 	depends on FB && XEN
-	select FB_SYS_FILLRECT
-	select FB_SYS_COPYAREA
-	select FB_SYS_IMAGEBLIT
-	select FB_SYS_FOPS
-	select FB_DEFERRED_IO
+	select FB_SYS_HELPERS_DEFERRED
 	select XEN_XENBUS_FRONTEND
 	default y
 	help