boards: beagley_ai_j722s_mcu_r5f0_0: Add IPC support

Add IPC memory and mailbox chosen properties. The mailbox channels
used are as expected by Linux.

Signed-off-by: Andrew Davis <afd@ti.com>

Author: glneo

boards/beagle/beagley_ai/beagley_ai_j722s_mcu_r5f0_0.dts

@@ -19,6 +19,8 @@
 		zephyr,sram = &atcm;
 		zephyr,console = &uart1;
 		zephyr,shell-uart = &uart1;
+		zephyr,ipc = &ipc0;
+		zephyr,ipc_shm = &ddr0;
 	};
 
 	cpus {
@@ -43,6 +45,12 @@
 		reg = <0xa1200000 DT_SIZE_M(14)>;
 		zephyr,memory-region = "DRAM";
 	};
+
+	ipc0: ipc {
+		compatible = "zephyr,mbox-ipm";
+		mboxes = <&mbox1 0>, <&mbox1 1>;
+		mbox-names = "tx", "rx";
+	};
 };
 
 &uart1 {