ARM: davinci: omapl138-hawk: add aemif & nand support

We now have support for aemif & nand from board files. As an example
add support for nand to da850-hawk.

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