Fix QGraphicsSceneEvents position translations to send to IPC

On QGraphicsSceneMouseEvent and QGraphicsSceneHoverEvent, the event
position provided to IPC was wrong. The calculation comes from
MouseEventEater, that was translating QMouseEvent to scene events
considering event global position was the absolute window position.

Updated also the mouse and hover event calculations as they were
tested on top of this wrong calculation in desktop.
Open-webOS-DCO-1.0-Signed-off-by: Jose Dapena Paz <jose.dapena@palm.com>

Change-Id: I8aabc9729714f0770ff7270f0f5b029af0ce5d46
Reviewed-on: http://g2g.palm.com/1641
Reviewed-by: Build Verification
Reviewed-by: Jose Dapena <jose.dapena@palm.com>
Tested-by: Jose Dapena <jose.dapena@palm.com>
Reviewed-by: Eric Blade <eric.blade@palm.com>
Reviewed-by: Vivek Sekar <vivek.sekar@lge.com>
Tested-by: Vivek Sekar <vivek.sekar@lge.com>
Reviewed-by: Roger Stringer <roger.stringer@lge.com>