[FS#1141] Don't show WAN status on Luci Overview page if there are no WAN interfaces

[LEDE Bugs]

The following task is now closed:

FS#1141 - Don't show WAN status on Luci Overview page if there are no WAN interfaces
User who did this - Jo-Philipp Wich (jow-)

Reason for closing: Not a bug
More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1141