Fix undefined reference to ble_svc_gap_device_name_set when GATT server is disabled

[iranl]

Since commit espressif/esp-idf@a58ce39 (included in v5.5-RC1) the function ble_svc_gap_device_name_set will not be defined in esp-idf when CONFIG_BT_NIMBLE_GATT_SERVER=n and compilation of esp-nimble-cpp will fail as a result.

This PR makes calling ble_svc_gap_device_name_set conditional on CONFIG_BT_NIMBLE_GAP_SERVICE in line with the examples in esp-idf master (see the above commit)

[h2zero]

Thanks, but this will also prevent the ability to change the name if that macro is not defined, such as when using an older NimBLE/IDF version. We should check if it is defined at all first then check the value.

[iranl]

CONFIG_BT_NIMBLE_GAP_SERVICE was introduced in IDF 5.1 and setting ble_svc_gap_device_name_set shouldn't have any effect when CONFIG_BT_NIMBLE_GAP_SERVICE=n since that time. It will only give a compilation error starting with IDF 5.5 though.

But I get your point for IDF 5.0 and below.

Imho most obvious solution would be to change the macro to:
#if !defined(ESP_IDF_VERSION) || ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(5, 5, 0) || CONFIG_BT_NIMBLE_GAP_SERVICE

So this should only affect IDF 5.5 and up.

[h2zero]

Thanks!