Allow the user to specify the path to an initrd/initramfs file which will be loaded in memory after the DTB. The load address for this data will be passed to Linux via DeviceTree. Change-Id: I52e12b9b88ab415fe3b318a6359026651667f3c6 Signed-off-by: Alistair Delva <adelva@google.com> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54186 Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Reviewed-by: Richard Cooper <richard.cooper@arm.com> Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com> Tested-by: kokoro <noreply+kokoro@google.com>