mtd: onenand: add workaround for SYNC_WRITE mode

Some chips fails to identify properly when SYNC_WRITE mode is enabled
(the example is OneNAND on S5PC110 SoC). This patch adds a workaround
for such chips.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>