dt-bindings: Drop required 'interrupt-parent'

'interrupt-parent' is never required as it can be in a parent node or a
parent node itself can be an interrupt provider. Where exactly it lives is
outside the scope of a binding schema.

Signed-off-by: Rob Herring <[e-mail]>
Acked-by: Lee Jones <[e-mail]>
Acked-by: Bartosz Golaszewski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/gpio/toshiba,gpio-visconti.yaml

···
   - gpio-controller
   - interrupt-controller
   - "#interrupt-cells"
-  - interrupt-parent
 
 additionalProperties: false
 

Documentation/devicetree/bindings/mailbox/ti,omap-mailbox.yaml

···
         compatible:
           enum:
             - ti,am654-mailbox
-    then:
-      required:
-        - interrupt-parent
-
-  - if:
-      properties:
-        compatible:
-          enum:
-            - ti,am654-mailbox
             - ti,am64-mailbox
     then:
       properties:

Documentation/devicetree/bindings/mfd/cirrus,madera.yaml

···
   - '#gpio-cells'
   - interrupt-controller
   - '#interrupt-cells'
-  - interrupt-parent
   - interrupts
   - AVDD-supply
   - DBVDD1-supply

Documentation/devicetree/bindings/net/lantiq,etop-xway.yaml

···
 required:
   - compatible
   - reg
-  - interrupt-parent
   - interrupts
   - interrupt-names
   - lantiq,tx-burst-length

Documentation/devicetree/bindings/net/lantiq,xrx200-net.yaml

···
 required:
   - compatible
   - reg
-  - interrupt-parent
   - interrupts
   - interrupt-names
   - "#address-cells"

Documentation/devicetree/bindings/pci/sifive,fu740-pcie.yaml

···
   - num-lanes
   - interrupts
   - interrupt-names
-  - interrupt-parent
   - interrupt-map-mask
   - interrupt-map
   - clocks

Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml

···
   - reg-names
   - "#interrupt-cells"
   - interrupts
-  - interrupt-parent
   - interrupt-map
   - interrupt-map-mask
   - bus-range