dt-bindings: interrupt-controller: ti,sci-intr: Fix missing reg property in the binding

Fix the following warning in dtbs_check
interrupt-controller@a00000: Unevaluated properties are not allowed ('reg' was unexpected)

Add the reg property in the schema.
Signed-off-by: Apurva Nandan <a-nandan@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220819190729.32358-4-a-nandan@ti.com

Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.yaml

@@ -58,6 +58,9 @@ properties:
         1 = If intr supports edge triggered interrupts.
         4 = If intr supports level triggered interrupts.
 
+  reg:
+    maxItems: 1
+
   interrupt-controller: true
 
   '#interrupt-cells':