[MTD] NAND: Fix the broken dynamic array allocations

Reverting the change from 1.136 to 1.137 (back to static allocation of ecc
arrays) due to stack corruption and ecc errors.

Signed-off-by: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>