Merge Tegra clk changes into next/dt64

These are a prerequisite to some of the tegra DT changes,
and got merged as part of tegra-for-4.8-clk into clk-next.

* commit 'e452b818':
  clk: tegra: Enable sor1 and sor1_src on Tegra210
  clk: tegra: Squash sor1 safe/brick/src into a single mux
  clk: tegra: Disable spread spectrum on pll_d2
  clk: tegra: Fixup post dividers on Tegra210