nand: lpc32xx: add hardware ECC support

Incorporate NAND SLC hardware ECC support from legacy LPCLinux NXP BSP.
The code taken from the legacy patch is:
- lpc32xx SLC NAND driver (hardware ECC support)
- lpc3250 header file missing SLC NAND registers definition

The legacy driver was updated and clean-up as part of the integration with the existing NAND SLC driver.

Signed-off-by: Sylvain Lemieux <slemieux@tycoint.com>
Tested-by: Vladimir Zapolskiy <vz@mleia.com>