target/loongarch: Use sys_state in cpu_helper.c when accessing CSR registers When accessing CSR register in file cpu_helper.c, use sys_state rather than env. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Reviewed-by: Philippe Mathieu-Daudé <philmd@mailo.com> Tested-by: Song Gao <gaosong@loongson.cn> Message-ID: <20260605082552.175336-4-maobibo@loongson.cn> Signed-off-by: Song Gao <gaosong@loongson.cn>