da850/omap-l138: Add support for NAND SPL This patch adds configuration required for NAND SP on DA850/OMAP-L138. Tested-by: Christian Riesch <christian.riesch@omicron.at> Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com> Signed-off-by: Rajashekhara, Sudhakar <sudhakar.raj@ti.com> Signed-off-by: Hadli, Manjunath <manjunath.hadli@ti.com>