target/riscv: Use RISCVException as return type for all csr ops

target/riscv: Use RISCVException as return type for all csr ops

The real return value type has been converted to RISCVException,
but some function declarations still not. This patch makes all
csr operation declarations use RISCVExcetion.

Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240130110844.437-1-zhiwei_liu@linux.alibaba.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>