arm: gic-v3: Scan for subnodes

According to the binding [1] the ITS node should be a subnode of the
GICv3 node. Since the ITS node has it's own driver, manually probe for
possible subnodes after binding since dm_scan_fdt() is not recursive.

1: https://www.kernel.org/doc/Documentation/devicetree/bindings/interrupt-controller/arm%2Cgic-v3.txt

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
diff --git a/arch/arm/lib/gic-v3-its.c b/arch/arm/lib/gic-v3-its.c
index 51cc239..34f05e9 100644
--- a/arch/arm/lib/gic-v3-its.c
+++ b/arch/arm/lib/gic-v3-its.c
@@ -232,6 +232,9 @@
 	.id		= UCLASS_IRQ,
 	.of_match	= gic_v3_ids,
 	.ops		= &arm_gic_v3_ops,
+#if CONFIG_IS_ENABLED(OF_REAL)
+	.bind		= dm_scan_fdt_dev,
+#endif
 	ACPI_OPS_PTR(&gic_v3_acpi_ops)
 };