Right now the pcap core driver passes a reference to its pcap data abusing the
subdrivers platform drvdata, this is not good.

Get the reference directly from the parent device.

This change was suggested by Mark Brown in
http://www.spinics.net/lists/linux-input/msg04285.htmlSigned-off-by: Antonio Ospite <ospite@studenti.unina.it>
Cc: Daniel Ribeiro <drwyrm@gmail.com>
Cc: guiming zhuo <gmzhuo@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>