staging: media: tegra-video: move syncpt init/free to a per-soc op
tegra_channel_host1x_syncpt_init() gets the host1x syncpts needed for the
Tegra210 implementation, and tegra_channel_host1x_syncpts_free() puts
them.
Tegra20 needs to get and put a different syncpt. In preparation for adding
Tegra20 support, move these functions to new ops in the soc-specific
`struct tegra_vi_ops` .