target/riscv/cpu: move priv spec functions to tcg-cpu.c

target/riscv/cpu: move priv spec functions to tcg-cpu.c

Priv spec validation is TCG specific. Move it to the TCG accel class.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20230925175709.35696-20-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>