target/riscv: Separate priv from mmu_idx

target/riscv: Separate priv from mmu_idx

Currently it's assumed the 2 low bits of mmu_idx map to privilege mode,
this assumption won't last as we are about to add more mmu_idx. Here an
individual priv field is added into TB_FLAGS.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Fei Wu <fei2.wu@intel.com>
Message-Id: <20230324054154.414846-2-fei2.wu@intel.com>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Tested-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-Id: <20230325105429.1142530-7-richard.henderson@linaro.org>
Message-Id: <20230412114333.118895-7-richard.henderson@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>