staging: nvec: add device tree support

This adds device tree support to the nvec driver. By using this method
it is no longer necessary to specify platform data through a board
file.

Signed-off-by: Marc Dietrich <marvin24@gmx.de>
Acked-by: Stephen Warren <swarren@nvidia.com>
Cc: Julian Andres Klode <jak@jak-linux.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>