List of files: 
 arm-trusted-firmware
          DDR_fw : <PATH>/arm-trusted-firmware/ddr/ddr_pmu-stm32mp257f-phyflex-fpsc-g-som-4Gb-optee-programmer-usb.bin
Fip tool command:
CMD> fiptool create   \ 
	--ddr-fw <PATH>/arm-trusted-firmware/ddr/ddr_pmu-stm32mp257f-phyflex-fpsc-g-som-4Gb-optee-programmer-usb.bin   \ 
	<PATH>/fip/fip-stm32mp257f-phyflex-fpsc-g-som-4Gb-ddr-optee-programmer-usb.bin