arm64: dts: ti: k3-am654-base-board: Add mailboxes to R5Fs

Add the required 'mboxes' property to both the R5F processors on all the
TI K3 AM65x boards. The mailboxes and some shared memory are required
for running the Remote Processor Messaging (RPMsg) stack between the
host processor and each of the R5Fs. The chosen sub-mailboxes match the
values used in the current firmware images. This can be changed, if
needed, as per the system integration needs after making appropriate
changes on the firmware side as well.

Note that the R5F Core1 resources are needed and used only when the
R5F cluster is configured for Split-mode.
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20201029033802.15366-3-s-anna@ti.com

arch/arm64/boot/dts/ti/k3-am654-base-board.dts

 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (C) 2016-2018 Texas Instruments Incorporated - https://www.ti.com/
+ * Copyright (C) 2016-2020 Texas Instruments Incorporated - https://www.ti.com/
  */
 
 /dts-v1/;
@@ -441,6 +441,14 @@ &mailbox0_cluster11 {
 	status = "disabled";
 };
 
+&mcu_r5fss0_core0 {
+	mboxes = <&mailbox0_cluster0 &mbox_mcu_r5fss0_core0>;
+};
+
+&mcu_r5fss0_core1 {
+	mboxes = <&mailbox0_cluster1 &mbox_mcu_r5fss0_core1>;
+};
+
 &ospi0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&mcu_fss0_ospi0_pins_default>;