target/riscv: Update the privilege field for sscofpmf CSRs

target/riscv: Update the privilege field for sscofpmf CSRs

The sscofpmf extension was ratified as a part of priv spec v1.12.
Mark the csr_ops accordingly.

Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Message-Id: <20220824221701.41932-6-atishp@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>