dma-buf/sync_file: de-stage sync_file

sync_file is useful to connect one or more fences to the file. The file is
used by userspace to track fences between drivers that share DMA bufs.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
new file mode 100644
index 0000000..9824bc4
--- /dev/null
+++ b/drivers/dma-buf/Kconfig
@@ -0,0 +1,11 @@
+menu "DMABUF options"
+
+config SYNC_FILE
+	bool "sync_file support for fences"
+	default n
+	select ANON_INODES
+	select DMA_SHARED_BUFFER
+	---help---
+	  This option enables the fence framework synchronization to export
+	  sync_files to userspace that can represent one or more fences.
+endmenu