KVM: riscv: selftests: Add get-reg-list test

get-reg-list test is used to check for KVM registers regressions
during VM migration which happens when destination host kernel
missing registers that the source host kernel has. The blessed
list registers was created by running on v6.5-rc3

Signed-off-by: Haibo Xu <haibo1.xu@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>