dt-binding: ti: am65x-cpts: add assigned-clock and power-domains props

The CPTS clock is usually a clk-mux which allows to select CPTS reference
clock by using 'assigned-clock-parents', 'assigned-clocks' DT properties.
Also depending on integration the power-domains has to be specified to
enable CPTS IP.

Hence add 'assigned-clock-parents', 'assigned-clocks' and 'power-domains'
properties to the CPTS DT bindings to avoid dtbs_check warnings:
cpts@310d0000: 'assigned-clock-parents', 'assigned-clocks' do not match any of the regexes: 'pinctrl-[0-9]+'
cpts@310d0000: 'power-domains' does not match any of the regexes: 'pinctrl-[0-9]+'

Signed-off-by: Grygorii Strashko <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/devicetree/bindings/net/ti,k3-am654-cpts.yaml

···
     items:
       - const: cpts
 
+  assigned-clock-parents: true
+
+  assigned-clocks: true
+
+  power-domains:
+    maxItems: 1
+
   ti,cpts-ext-ts-inputs:
     $ref: /schemas/types.yaml#/definitions/uint32
     maximum: 8