gdbstub: Simplify #ifdef'ry in helpers.h

Slightly simplify by checking NEED_CPU_H definition in header.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240322161439.6448-2-philmd@linaro.org>
1 file changed