board: freescale: lx2160a: remove the PL01X device instantiation

There is no need for the board file to instantiate a PL01X platform
device anymore. This is all taken care of by the DM code which now will
probe the device based on the DT node.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>