WlanVAP expects an incorrect WLAN interface

[wwahammy]

In https://github.com/qca/boardfarm/blob/master/tests/wifi_vap_test.py, there's a couple lines where VAP's are added on WLAN interfaces wifi0 and wifi1 (https://github.com/qca/boardfarm/blob/master/tests/wifi_vap_test.py#L21). In some cases these interfaces, are not wifi0 and wifi1 but instead are wlan0 and wlan1. I presume there are other possibilities as well.

WlanVAP should either allow you to pass in a WLAN interfaces names or, better yet, figures the interfaces out on its own.

[mattsm]

Need to extract these from UCI... but also wifi tests and setup need a lot of work in general though as well.