* STM32 DDR Performance Monitor (DDRPERFM)

Required properties:
- compatible: must be "st,stm32-ddr-pmu".
- reg: physical address and length of the registers set.
- clocks: list of phandles and specifiers to all input clocks listed in
	  clock-names property.
- clock-names: "bus" corresponds to the DDRPERFM bus clock and "ddr" to
	       the DDR frequency.

Example:
	ddrperfm: perf@5a007000 {
		compatible = "st,stm32-ddr-pmu";
		reg = <0x5a007000 0x400>;
		clocks = <&rcc DDRPERFM>, <&scmi0_clk CK_SCMI0_PLL2_R>;
		clock-names = "bus", "ddr";
	};