target/riscv: Add csr support for svadu

Add ext_svadu property
Add HADE field in *envcfg:
* menvcfg.HADE is read-only zero if Svadu is not implemented.
* henvcfg.HADE is read-only zero if menvcfg.HADE is zero.

Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20230224040852.37109-4-liweiwei@iscas.ac.cn>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
3 files changed