[MTD NAND] Allocate chip->buffers separately to allow it to be overridden

In particular, the board driver might need it to be DMAable.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index a612c4e..9402653 100644
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -759,7 +759,7 @@
 	struct nand_chip *this = mtd->priv;
 
 	bd->options &= ~NAND_BBT_SCANEMPTY;
-	return create_bbt(mtd, this->buffers.databuf, bd, -1);
+	return create_bbt(mtd, this->buffers->databuf, bd, -1);
 }
 
 /**