ARM: shmobile: r8a73a4 dtsi: Add PM domain support
Add a device node for the System Controller, with subnodes that
represent the hardware power area hierarchy.
Hook up all devices to their respective PM domains.
Add a minimal device node for the Coresight-ETM hardware block, and
hook it up to the D4 PM domain, so the R-Mobile System Controller
driver can keep the domain powered, until the new Coresight code
handles runtime PM.
The System Controller is also used by the R-Mobile Reset driver, which
can now restart the system.