Input: Propagate hardware event timestamp to evdev.

Convey hardware timestamp associated with the current event packet.
The use of these event codes by hardware drivers is optional.
Used to reduce jitter and improve velocity tracking in ABS_MT devices.

Change-Id: I89f3a958944f6a2979964ee372e61bad448061b6
Signed-off-by: Sasha Levitskiy <sanek@google.com>