This reverts commit c49836f05a.
The commit is wrong and its approach actually does not work. Let's
revert it in order to add the feature with a clean patch.
Fixes: c49836f05a ("mtd: rawnand: sunxi: Add A23/A33 DMA support")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>