wiasane: Respect reference count within ExitScannerSession
wiasane: Do not close session if ADF scan is in progress
wiasane: Handle multiple SCAN_FIRST calls during ADF load and scan

This fixes the invalid ADF logic introduced with commit
fc5776ab54b3e3d54a799d3f95c93f562235dc34.
wiasane: Skip SCAN_FIRST if ADF is already loaded