NAND: Don't walk past end of oobfree[]

When computing oobavail from the list of free areas in the OOB,
don't assume there will always be an unused slot at the end.
This syncs up with the kernel NAND driver.

Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>

drivers/mtd/nand/nand_base.c

@@ -2871,7 +2871,8 @@ int nand_scan_tail(struct mtd_info *mtd)
 	 * the out of band area
 	 */
 	chip->ecc.layout->oobavail = 0;
-	for (i = 0; chip->ecc.layout->oobfree[i].length; i++)
+	for (i = 0; chip->ecc.layout->oobfree[i].length
+			&& i < ARRAY_SIZE(chip->ecc.layout->oobfree); i++)
 		chip->ecc.layout->oobavail +=
 			chip->ecc.layout->oobfree[i].length;
 	mtd->oobavail = chip->ecc.layout->oobavail;