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

The KVM RISC-V allows Sscofpmf extension for Guest/VM so let us
add this extension to get-reg-list test.

Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-20-atishp@rivosinc.com


Signed-off-by: Anup Patel <anup@brainfault.org>