HID: sony: Handle multiple touch events input record

Read the touch history field in the HID descriptor and use this value
to determine how many touch events to read from the report. As part
of this patch, we did a first attempt of making the offset calculation
code less magical.

Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>