Clear the ts event buffer at appropriate points in ts_calibrate
Clear the ts event buffer at appropriate points in ts_calibrate

Fixes the issue where an accidental double-tap at one coordinate results in
having to restart the calibration, since the second tap gets read as the next
coordinate for the calibration.  Patch courtesy MontaVista Software, Inc.

Signed-off-by: Chris Larson <8cf06b7089d5169434d5def8b2d1c9c9c95f6e71@kergoth.com>

kergoth/tslib,pssc/tslib,kobolabs/tslib,leighmurray/tslib,jaretcantu/tslib,etmatrix/tslib,lin2724/tslib,etmatrix/tslib,jaretcantu/tslib,folkien/tslib,leighmurray/tslib,vpeter4/tslib,kergoth/tslib,kobolabs/tslib,kobolabs/tslib,vpeter4/tslib,etmatrix/tslib,pssc/tslib,folkien/tslib,kergoth/tslib,kergoth/tslib,pssc/tslib,lin2724/tslib