target/riscv: H extension depends on I extension

target/riscv: H extension depends on I extension

Add check for "H depends on an I base integer ISA with 32 x registers"
which is stated at the beginning of chapter 8 of the riscv-privileged
spec(draft-20220717)

Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-Id: <20220718130955.11899-3-liweiwei@iscas.ac.cn>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>