netcardconfig: Add comments to make code more readable

netcardconfig: Add comments to make code more readable

Add comments before and after the very long if-stanzas in the
configiface function (which should be refactored by the way).

Also moved WLDEVICECOUNT= with an `iwconfig` call into the if-scope of
'Setup wireless options' to avoid an unneeded iwconfig call.
WLDEVICECOUNT is only used in that scope.