input: touchscreen:

If the hardware signals that it is
cking more contacts than it is currently reporting, the driver should use
a BTN_TOOL_*TAP event to inform userspace of the total number of contacts
being tracked by the hardware at that moment.  The driver should do this by
explicitly sending the corresponding BTN_TOOL_*TAP event and setting
use_count to false when calling input_mt_report_pointer_emulation().