FROMLIST: dma-buf: add support for virtio exported objects

This change adds a new dma-buf operation that allows dma-bufs to be used
by virtio drivers to share exported objects. The new operation allows
the importing driver to query the exporting driver for the UUID which
identifies the underlying exported object.

Signed-off-by: David Stevens <stevensd@chromium.org>

BUG=b:136269340
TEST=boot ARCVM and launch play store

Signed-off-by: Keiichi Watanabe <keiichiw@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2059086


Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: David Stevens <stevensd@chromium.org>
Commit-Queue: David Stevens <stevensd@chromium.org>
Bug: 153580313
Link: https://lore.kernel.org/lkml/20200311112004.47138-2-stevensd@chromium.org/


Change-Id: Ifb429e36ebbba9feead6fd1792fbefa9ca097f0c
Signed-off-by: Lingfeng Yang <lfy@google.com>