lpc32xx: move common SLC NAND defines to arch/config.h

A number of LPC32xx SLC NAND defines is dictated by controller
hardware limits and OOB layout is defined by operating system, the
definitions are common for all users. Since those macro are used
in out of NAND SLC driver code (simple NAND SPL framework), they can
not be placed into the driver, therefore move them from board config
files to arch/config.h

The change also adds OOB layout details specific to small page NAND
devices taken from Linux kernel.

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