use LED_GPIO not 0

[taunoe]

Use defined LED_GPIO not 0

[peterharperuk]

Sorry - you'll have to push to develop not master

[lurch]

Looks like the same thing affects https://github.com/raspberrypi/pico-examples/blob/develop/pico_w/wifi/iperf/picow_iperf.c#L98 too? Some of the other picow examples use cyw43_arch_gpio_put rather than cyw43_gpio_set - most of them use CYW43_WL_GPIO_LED_PIN but https://github.com/raspberrypi/pico-examples/blob/develop/pico_w/wifi/freertos/iperf/picow_freertos_iperf.c#L53 uses a hardcoded 0.

EDIT: And CYW43_WL_GPIO_LED_PIN is defined in https://github.com/raspberrypi/pico-sdk/blob/develop/src/boards/include/boards/pico_w.h#L98