mtd: nand: rename "no_bbt" descriptors to "no_oob"

These descriptors are for BBT's that don't use OOB; the "no_bbt" name doesn't
really make sense.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>