Update unavailable bands in SoftAp config

After removing the unavailable bands, update the
band information in softAp config.
Fall back to Single AP mode only if one band is
present in SoftAp config - band array.

Bug: 282609630
Test: atest SoftApManagerTest
Test: atest ApConfigUtilTest
Test: Manual - Hotspot on/off via UI and adb shell command
Change-Id: I63665d2af3dbf2da932070303ee4d288d8a3ee86
4 files changed