WPS: Merge mixed-WPA/WPA2 credentials if received in same session
Some deployed APs send two credentials when in mixed-WPA/WPA2
configuration; one for the WPA-Personal/TKIP and the other for
WPA2-Personal/CCMP. Previously, this would result in two network blocks
getting added for the single AP. This can be somewhat confusing and
unnecessary, so merge such credentials into a single one that allows
both WPA and WPA2 to be used.