[scripts][do-qemuriscv] synchronize with options available from arm version
[scripts][do-qemuriscv] synchronize with options available from arm version

Most notably the ability to specify the disk image

hollanderic/lkstuff,hollanderic/lkstuff,hollanderic/lkstuff,hollanderic/lkstuff,littlekernel/lk,littlekernel/lk,littlekernel/lk,littlekernel/lk