[nrf fromlist] boards: nordic: nrf54h20dk: ipc to cpusys with unbound

Unbound feature in IPC with cpusys will be detected.
This is needed to enable IPC link renewal.

Upstream PR #: 92587

Signed-off-by: Łukasz Stępnicki <[email protected]>

Author: lstnl

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20-ipc_conf.dtsi

@@ -32,6 +32,7 @@
 
 		cpuapp_cpusys_ipc: ipc-2-12 {
 			compatible = "zephyr,ipc-icmsg";
+			unbound = "detect";
 			status = "disabled";
 			dcache-alignment = <32>;
 			mboxes = <&cpuapp_bellboard 6>,
@@ -56,6 +57,7 @@
 
 		cpurad_cpusys_ipc: ipc-3-12 {
 			compatible = "zephyr,ipc-icmsg";
+			unbound = "detect";
 			status = "disabled";
 			dcache-alignment = <32>;
 			mboxes = <&cpurad_bellboard 6>,