NAND: Update check condition for nand_read_page_hwecc API

The patch updates the check condition for determining
whether the ECC corrections has failed.
This makes it similar to what is in the kernel NAND driver.

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

drivers/mtd/nand/nand_base.c

@@ -1062,7 +1062,7 @@ static int nand_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip,
 		int stat;
 
 		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
-		if (stat == -1)
+		if (stat < 0)
 			mtd->ecc_stats.failed++;
 		else
 			mtd->ecc_stats.corrected += stat;