FIXUP: CHROMIUM: virtwl: add virtwl driver

0day reports:

drivers//virtio/virtio_wl.c: In function do_send:
drivers//virtio/virtio_wl.c:790:9: warning:
	ret may be used uninitialized in this function [-Wmaybe-uninitialized]

BUG=chromium:738638
TEST=Build driver with W=1

Change-Id: I83afb8b7e754bd80e660ec772671a20a87df5624
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/802255
Reviewed-by: Dylan Reid <dgreid@chromium.org>