mtd: nand: tests: fix regression introduced in mtd_nandectest

Offending Commit: 6e941192 "mtd: nand: return consistent error codes in
ecc.correct() implementations"

The new error code was not being handled properly in double bit error
detection.
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/tests/mtd_nandecctest.c

@@ -187,7 +187,7 @@ static int double_bit_error_detect(void *error_data, void *error_ecc,
 	__nand_calculate_ecc(error_data, size, calc_ecc);
 	ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
 
-	return (ret == -1) ? 0 : -EINVAL;
+	return (ret == -EBADMSG) ? 0 : -EINVAL;
 }
 
 static const struct nand_ecc_test nand_ecc_test[] = {