davinci: mityomapl138: Use correct id for NAND controller

For the MityDSP-L138/MityARM-1808 SOMS, the NAND controller id (which needs
to correspond to the chipselect, and is used for controlling the HW ECC
computation) is not correct.  Fix it.

Signed-off-by: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>