Input: egalax_ts - ABS_MT_POSITION_Y not reported well

The egalax_ts touchscreen modul not report ABS_MT_POSITION_Y proper.
As result it may be, that upper software levels only receive x coordinates well.

Signed-off-by: Heiko Abraham <abrahamh@web.de>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>