tune: make tune_iface::scan_progress a pure virtual function
tune: make tune_iface::scan_progress a pure virtual function

Signed-off-by: Michael Ira Krufky <00524723a60798c74a43fcc620c25dd7b9ece078@linuxtv.org>

pashamesh/libdvbtee,pashamesh/libdvbtee,anshul1912/libdvbtee,mkrufky/libdvbtee,mkrufky/libdvbtee,mkrufky/libdvbtee,mkrufky/libdvbtee,anshul1912/libdvbtee,mkrufky/libdvbtee,pashamesh/libdvbtee,anshul1912/libdvbtee