This adds an example user-space FunctionFS driver which
implements a source/sink interface used for testing.
Signed-off-by: NMichal Nazarewicz <m.nazarewicz@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>