@pin is an input where we connect a device output.
Rename it @input_pin to simplify the documentation.

Reviewed-by: Yanan Wang <wangyanan55@huawei.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20211218130437.1516929-5-f4bug@amsat.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>