Running workloads likely causes some content to be written to the disk image, e.g., `m5 readfile`. However, on riscv boards, the default kernel param specifies the disk image to be read-only. This change changes this param so that the disk image is read-write by default. Change-Id: I414e483ad11d747f34433560e32a8f91a425ce7e Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/65194 Maintainer: Jason Lowe-Power <power.jg@gmail.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>