mtd: docg4: ecc.read_page() returns 0 on uncorrectable errors

Currently the docg4's ecc.read_page() method returns -EBADMSG when
uncorrectable bitflips occur.  This is wrong; 0 should be returned in
this case.  An error code should only be returned by this method in the
case of a hardware error (probably -EIO).
Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/docg4.c

@@ -776,6 +776,8 @@ static int read_page(struct mtd_info *mtd, struct nand_chip *nand,
 	}
 
 	writew(0, docptr + DOC_DATAEND);
+	if (bits_corrected == -EBADMSG)	  /* uncorrectable errors */
+		return 0;
 	return bits_corrected;
 }