vmwgfx: Remove dmabuf check in present ioctl

Doesn't protect any error code and only gets in the way of debugging.

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