target/riscv: remove RISCV_FEATURE_PMP

target/riscv: remove RISCV_FEATURE_PMP

RISCV_FEATURE_PMP is being set via riscv_set_feature() by mirroring the
cpu->cfg.pmp flag. Use the flag instead.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Message-ID: <20230222185205.355361-8-dbarboza@ventanamicro.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>