mtd: pxa3xx_nand: remove the flash info in driver structure

After probe, all info already transfer to driver structure.
There is no need to keep the original flash info.
So that we could safely free the flash info in memory, which may grows
larger when more flash is suported.

Signed-off-by: Lei Wen <leiwen@marvell.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>