This clock was previously called sor1_src and was modelled as an input
to the sor1 module clock. However, it's really an output clock that can
be fed either from the safe, the sor1_pad_clkout or the sor1 module
clocks. sor1 itself can take input from either of the display PLLs.

The same implementation for the sor1_out clock is used on Tegra186, so
this nicely lines up both SoC generations to deal with this clock in a
uniform way.
Signed-off-by: Thierry Reding <treding@nvidia.com>