NAND: DaVinci: V2 Adding 4 BIT ECC support

This patch adds 4 BIT ECC support in the DaVinci NAND
driver. Tested on both the DM355 and DM365.

Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>