ARM: tegra: remove a conditional for CSITE rate

There's already an SoC-specific conditional in cpu.h to determine the
PLLP rate. Define the CSITE clock rate inside the same conditional, so
that we can remove a conditional from clock_enable_coresight(). This
means one less place to update the code for new SoCs.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>