char: hwicap: Remove unnecessary dev_set_drvdata()

Driver core clears the driver data to NULL after device_release
or on probe failure, so just remove it from here.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>