forked from Mirrors/opensbi

We add the menvcfg CSR as a HART feature and detect it at boot time using traping mechanism. Signed-off-by: Atish Patra <atishp@rivosinc.com> Signed-off-by: Anup Patel <apatel@ventanamicro.com> Reviewed-by: Xiang W <wxjstz@126.com>