We don't need to fill the full pic[] array if we only use
few of the interrupt lines. Directly call qdev_get_gpio_in()
when necessary.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20201107193403.436146-6-f4bug@amsat.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>