mtd: OneNAND: Fix multi block erase support at 4KiB pagesize

Original 4KiB pagesize chip (SLC) doesn't support Multi block erase at Spec.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>