staging/olpc_dcon: Remove obsolete cleanup for clientdata

A few new i2c-drivers came into the kernel which clear the clientdata-pointer
on exit or error. This is obsolete meanwhile, the core will do it.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Andres Salomon <dilinger@queued.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Marek Belisko <marek.belisko@open-nandra.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>