ARM: tegra: add missing clock documentation to DT bindings

Many of the Tegra DT binding documents say nothing about the clocks or
clock-names properties, yet those are present and required in DT files.
This patch simply updates the documentation file to match the implicit
definition of the binding, based on real-world DT content.

All Tegra bindings that mention clocks are updated to have consistent
wording and formatting of the clock-related properties.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-By: Terje Bergstrom <tbergstrom@nvidia.com>

Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt

@@ -9,6 +9,7 @@ Required properties:
 - compatible : Should contain "nvidia,tegra<chip>-pmc".
 - reg : Offset and length of the register set for the device
 - clocks : Must contain an entry for each entry in clock-names.
+  See ../clocks/clock-bindings.txt for details.
 - clock-names : Must include the following entries:
   "pclk" (The Tegra clock of that name),
   "clk32k_in" (The 32KHz clock input to Tegra).