mtd: nand: sunxi: make cur_off parameter optional in extra oob helpers

Allow for NULL cur_offs values when the caller does not know where the
NAND page register pointer points to.
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/sunxi_nand.c

@@ -956,7 +956,7 @@ static void sunxi_nfc_hw_ecc_read_extra_oob(struct mtd_info *mtd,
 	if (len <= 0)
 		return;
 
-	if (*cur_off != offset)
+	if (!cur_off || *cur_off != offset)
 		nand->cmdfunc(mtd, NAND_CMD_RNDOUT,
 			      offset + mtd->writesize, -1);
 
@@ -966,7 +966,8 @@ static void sunxi_nfc_hw_ecc_read_extra_oob(struct mtd_info *mtd,
 		sunxi_nfc_randomizer_read_buf(mtd, oob + offset, len,
 					      false, page);
 
-	*cur_off = mtd->oobsize + mtd->writesize;
+	if (cur_off)
+		*cur_off = mtd->oobsize + mtd->writesize;
 }
 
 static int sunxi_nfc_hw_ecc_write_chunk(struct mtd_info *mtd,
@@ -1021,13 +1022,14 @@ static void sunxi_nfc_hw_ecc_write_extra_oob(struct mtd_info *mtd,
 	if (len <= 0)
 		return;
 
-	if (*cur_off != offset)
+	if (!cur_off || *cur_off != offset)
 		nand->cmdfunc(mtd, NAND_CMD_RNDIN,
 			      offset + mtd->writesize, -1);
 
 	sunxi_nfc_randomizer_write_buf(mtd, oob + offset, len, false, page);
 
-	*cur_off = mtd->oobsize + mtd->writesize;
+	if (cur_off)
+		*cur_off = mtd->oobsize + mtd->writesize;
 }
 
 static int sunxi_nfc_hw_ecc_read_page(struct mtd_info *mtd,