wifi: Two AP instances use the same interface name

When device supports two AP interfaces (i.e. {AP, 2}. not a bridged case),
the AP interface name might be observed from the getPredefinedApIfaceNames.
Check if the interface name is used or not when creating a new interface.

Bug: 244387442
Test: Manual test by commands
adb shell cmd wifi start-softap tetheredAp open -b 2
adb shell cmd wifi start-lohs lohs open -b 5

Change-Id: I59b3796895ee09452a9650c4dc138ad9e143282e