[nrf fromlist] boards: 54h20: Support IPC between SEC and APP

Support IPC between SEC and APP. This is needed for PSA Crypto
support.

This patch is expected to be removed within a couple of weeks by the
ongoing work in NCSDK-32158.

Upstream PR #: 88285

Ref: NCSDK-NONE

Signed-off-by: Sebastian Bøe <[email protected]>

Author: SebastianBoe

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuapp_iron.dts

@@ -8,12 +8,24 @@
 
 /delete-node/&cpurad_rx_partitions;
 /delete-node/&cpuapp_rx_partitions;
-/delete-node/&cpusec_cpuapp_ipc;
 
 /* This is not yet an exhaustive memory map, and contain only a minimum required to boot
  * the application core.
  */
 
+/* Temporary until NCSDK-32158 */
+&cpusec_cpuapp_ipc {
+	status = "okay";
+	mbox-names = "tx", "rx";
+	tx-region = <&cpuapp_cpusec_ipc_shm>;
+	rx-region = <&cpusec_cpuapp_ipc_shm>;
+};
+
+/* Temporary until NCSDK-32158 */
+&cpusec_bellboard {
+	status = "okay";
+};
+
 &mram1x {
 	cpuapp_rx_partitions: cpuapp-rx-partitions {
 		compatible = "nordic,owned-partitions", "fixed-partitions";