devkit8000: Fix NAND SPL on boards with 256MB NAND

The devkit8000 ships with either a 128MB or 256MB NAND chip.  In
order for SPL to work with 256MB NAND CONFIG_SYS_NAND_5_ADDR_CYCLE
needs to be set.  After talking with Scott Wood this should be
safe to set even for smaller NAND chips.

Cc: Scott Wood <scottwood@freescale.com>
Cc: Frederik Kriewitz <frederik@kriewitz.eu>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Signed-off-by: Tom Rini <trini@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>