ti: k3: common: Add root domain node to platform topology

Actions may need to be taken by the last core when all clusters
have been shutdown. Add a top level root domain node to coordinate
this between clusters.

Signed-off-by: Andrew F. Davis <afd@ti.com>
diff --git a/plat/ti/k3/common/k3_topology.c b/plat/ti/k3/common/k3_topology.c
index a77c8f3..d7ac0a5 100644
--- a/plat/ti/k3/common/k3_topology.c
+++ b/plat/ti/k3/common/k3_topology.c
@@ -9,6 +9,7 @@
 
 /* The power domain tree descriptor */
 static unsigned char power_domain_tree_desc[] = {
+	PLATFORM_SYSTEM_COUNT,
 	PLATFORM_CLUSTER_COUNT,
 	K3_CLUSTER0_CORE_COUNT,
 #if K3_CLUSTER1_MSMC_PORT != UNUSED