Similar to the MSR RAPL interface, MMIO RAPL supports PL4 too, so add
MMIO RAPL PL4d support to the processor_thermal driver.

As a result, the powercap sysfs for MMIO RAPL will show a new "peak
power" constraint.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20240930081801.28502-7-rui.zhang@intel.com
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>