CHROMIUM: drm/vgem: remove dma_buf_attach from vgem

VGEM is not a real device but was pretending to be one to allow it to
use dma_buf_attach. This patch removes the need to use dma_buf_attach by
directly using the dma_buf_mmap api.

TEST=None
BUG=chromium:394868
CQ-DEPEND=CL:235791

Change-Id: I11cb6961ffcc85a3d081e755cf33864265fbcf38
Signed-off-by: Zach Reizner <zachr@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/235801
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
3 files changed