Modification to support PenMount 1610

Modification to input-raw.c to support PenMount 1610 as issue described in 
https://github.com/kergoth/tslib/issues/21

The touch signals is listed in the issue. Changes:
- Touch action is ended when within a SYN_REPORT there is no
ABS_X or ABS_Y and the pen down signal (BTN_TOUCH BTN_LEFT , value == 1)
is not called
- EV_ABS ABS_MT_WIDTH_MINOR is added as a pressure signal.