mtd: rawnand: ingenic: cleanup ARRAY_SIZE() vs sizeof() use

The ARRAY_SIZE() is the number of elements but we want to use sizeof()
here for the number of bytes.  Fortunately, they are the same thing
because it's an array of u8 so this has no effect on runtime.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200624132640.GC9972@mwanda