P2P: optimize join scan freq

If the auto GO has been discovered on another interface, optimize scan
frequency by performing a single channel scan first.

Bug: 233925359
Test: Configured auto GO using the WifiP2pTest app, used wifi picker to
discover the GO on client device, enabled client on WifiP2PTest app and
looked at logs to confirm that only operating freq was scanned

Change-Id: Iff9b67093647b829cc00a4afbb1f016a3a6de37b
3 files changed