Add support for Leon touch devices, which is the same as
slippy/falco/peppy/wolf on the same buses using the LynxPoint-LP I2C via
the i2c-designware-pci driver.

Based on the following patch:
https://chromium-review.googlesource.com/#/c/168351/Signed-off-by: NGene Chen <gene.chen@intel.com>
Reviewed-by: NBenson Leung <bleung@chromium.org>
Signed-off-by: NEnric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: NOlof Johansson <olof@lixom.net>