drm/vmwgfx: Use TTM handles instead of SIDs as user-space surface handles.

Improve the command verifier to catch all occurences of surface handles,
and translate to SIDs.

This way DMA buffers and 3D surfaces share a common handle space,
which makes it possible for the kms code to differentiate.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>