[ARM] pxa: update flash structure in onenand info

Since flash structure is changed from flash_platform_data to
onenand_platform_data in generic driver. Update the struct in saar
and ttc platform driver.

Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>