boards: nordic: nrf9280pdk: remove /delete-node line

Remove `/delete-node/ ipc-1-3;` as this has no effect on the context.

Signed-off-by: Giacomo Dematteis <giacomo.dematteis@nordicsemi.no>

Author: DematteisGiacomo

boards/nordic/nrf9280pdk/nrf9280pdk_nrf9280-ipc_conf_iron.dtsi

@@ -9,7 +9,6 @@
 / {
 	ipc {
 		/delete-node/ ipc-1-2;
-		/delete-node/ ipc-1-3;
 
 		cpusec_cpuapp_ipc: ipc-1-2 {
 			compatible = "nordic,ironside-call";