target/riscv: smstateen check for fcsr

target/riscv: smstateen check for fcsr

Implement the s/h/mstateen.fcsr bit as defined in the smstateen spec
and check for it when accessing the fcsr register and its fields.

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: <20230518175058.2772506-2-mchitale@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>