target/riscv: smstateen check for h/s/envcfg

target/riscv: smstateen check for h/s/envcfg

Accesses to henvcfg, henvcfgh and senvcfg are allowed only if the corresponding
bit in mstateen0/hstateen0 is enabled. Otherwise an illegal instruction trap is
generated.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Weiwei Li<liweiwei@iscas.ac.cn>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221016124726.102129-3-mchitale@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>