mtd: nand: choose correct chip name (ONFI bug)

We have the order of the conditional wrong for choosing the ONFI chip name
vs. the ID table name. Without this fix, we will almost *always* choose a
NULL string to print out instead of the correct one.

This has already been suggested by Matthieu Castet.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Acked-by: Florian Fainelli <ffainelli@freebox.fr>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>