dt-bindings: tegra: Add documentation for nvidia,tegra194-pmc

The Tegra194 power management controller has one additional register
aperture to be specified in the device tree node.

Signed-off-by: Mikko Perttunen <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>

Documentation/devicetree/bindings/arm/tegra/nvidia,tegra186-pmc.txt

···
 Required properties:
 - compatible: Should contain one of the following:
   - "nvidia,tegra186-pmc": for Tegra186
+  - "nvidia,tegra194-pmc": for Tegra194
 - reg: Must contain an (offset, length) pair of the register set for each
   entry in reg-names.
 - reg-names: Must include the following entries:
···
   - "wake"
   - "aotag"
   - "scratch"
+  - "misc" (Only for Tegra194)
 
 Optional properties:
 - nvidia,invert-interrupt: If present, inverts the PMU interrupt signal.