Implement a small abstraction interface to allow different versions of
VIC to be used transparently. An implementation will be chosen based on
the VIC version number reported by the DRM_TEGRA_IOCTL_OPEN_CHANNEL
IOCTL.
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>