clk: tegra: fix driver to match DT binding

enum tegra*_clk is intended to match the IDs listed in the Tegra clock
bindings. There are a few mismatches, which this patch fixes:

1) pll_s and cop were left out of the Tegra20 enum.

2) spdif_in and spdif_out were swapped relative to the Tegra30 binding.

3) i2cslow was misnamed as i2c_slow, and a duplicate i2cslow clock added
   to the Tegra30 enum.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>