aes2501: Harden against low finger pressure
aes2501: Harden against low finger pressure

Wait for 3 empty frames before stopping the scan

The driver used to stop the scan immediately after an empty frame
(by checking for hist sum == 0), but it is possible to get empty
frames in the middle of the scan due to low finger pressure.
Waiting for 3 empty frames stop the driver wrongly aborting the scan
too early.

https://bugs.freedesktop.org/show_bug.cgi?id=56715

FabriceSalvaire/libfprint-baspi,Gnate/libfprint,abhishekgahlot/libfprint,abhishekgahlot/libfprint,rmarku/libfprint,PDXostc/libfprint,Gnate/libfprint,jipumarino/libfprint,zOrg1331/libfprint,micw/libfprint,rmarku/libfprint,abhishekgahlot/fprint-bsapi,payden/libfprint,hyperair/fprint-bsapi,sbambrough/libfprint_extended,FabriceSalvaire/libfprint-baspi,hyperair/fprint-bsapi,sbambrough/libfprint_extended,ccsystems/libfprint,zOrg1331/libfprint,abhishekgahlot/fprint-bsapi,abhishekgahlot/fprint-bsapi,PDXostc/libfprint,zemen/libfprint,anarsoul/libfprint,zemen/libfprint,payden/libfprint,ccsystems/libfprint,freedesktop-unofficial-mirror/libfprint__libfprint,jipumarino/libfprint,abhishekgahlot/libfprint,yingted/etes603,iafilatov/libfprint,freedesktop-unofficial-mirror/libfprint__libfprint,sbambrough/libfprint_extended,Gnate/libfprint,zOrg1331/libfprint,ccsystems/libfprint,FabriceSalvaire/libfprint-baspi,rmarku/libfprint,zemen/libfprint,anarsoul/libfprint,micw/libfprint,jipumarino/libfprint,hyperair/fprint-bsapi,PDXostc/libfprint,micw/libfprint,freedesktop-unofficial-mirror/libfprint__libfprint,yingted/etes603,yingted/etes603,payden/libfprint