dt-bindings: rtc: rzn1: add optional second clock

The external crystal can be a second clock input. It is needed for the
SCMP counting method which allows using crystals different than 32768Hz.
It is also needed for an upcoming SoC which only supports the SCMP
method.

Signed-off-by: Wolfram Sang <[email protected]>
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>

Author: Wolfram Sang

Documentation/devicetree/bindings/rtc/renesas,rzn1-rtc.yaml

@@ -33,10 +33,14 @@ properties:
       - const: pps
 
   clocks:
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
 
   clock-names:
-    const: hclk
+    minItems: 1
+    items:
+      - const: hclk
+      - const: xtal
 
   power-domains:
     maxItems: 1