ARM: dts: AM4372: Add the wkup_m3_ipc node

Add the Wakeup M3 IPC device node for the wkup_m3_ipc driver on
AM4372 SoC. This node uses the IPC registers, part of the Control
Module, and is therefore added as a child of the scm node.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>