packages: k3screenctrl: fix WAN detection if virtual interfaces are used

* Use ifstatus to get interface info.

[DO NOT SUBMIT] mac80211: do not add new interface before bringing up if

  Typically LEDE removes all interfaces and re-add them when bringing
up wireless. However, brcmfmac does not allow removing interface
(at least on the firmwares I tested) and this will lead to error.
  After removing this line, the wireless will work as expected.

Start of the LEDE project