ARM: davinci: mityomapl138: specify the chipselect in davinci_nand_pdata

We now have the core_chipsel field in davinci_nand_pdata. Use it
instead of the platform_device id number.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>