dt-bindings: pinctrl: aspeed: Add reg property as a hint

The pinctrl node sits under a syscon device, and can assume offsets from
the base of the syscon based on the compatible. However, for devicetree
correctness allow a reg property to be specified, which an associated
driver may choose to use to discover associated resources.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>

Documentation/devicetree/bindings/pinctrl/aspeed,ast2400-pinctrl.yaml

@@ -22,6 +22,9 @@ description: |+
 properties:
   compatible:
     const: aspeed,ast2400-pinctrl
+  reg:
+    description: |
+      A hint for the memory regions associated with the pin-controller
 
 patternProperties:
   '^.*$':

Documentation/devicetree/bindings/pinctrl/aspeed,ast2500-pinctrl.yaml

@@ -23,6 +23,9 @@ description: |+
 properties:
   compatible:
     const: aspeed,ast2500-pinctrl
+  reg:
+    description: |
+      A hint for the memory regions associated with the pin-controller
   aspeed,external-nodes:
     minItems: 2
     maxItems: 2