iio: magnetometer: yas530: Fix memchr_inv() misuse

[ Upstream commit bb52d36 ]

The call to check if the calibration is all zeroes is doing
it wrong: memchr_inv() returns NULL if the the calibration
contains all zeroes, but the check is for != NULL.

Fix it up. It's probably not an urgent fix because the inner
check for BIT(7) in data[13] will save us. But fix it.

Fixes: de8860b ("iio: magnetometer: Add driver for Yamaha YAS530")
Reported-by: Jakob Hauser <jahau@rocketmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220501195029.151852-1-linus.walleij@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/iio/magnetometer/yamaha-yas530.c

@@ -639,7 +639,7 @@ static int yas532_get_calibration_data(struct yas5xx *yas5xx)
 	dev_dbg(yas5xx->dev, "calibration data: %*ph\n", 14, data);
 
 	/* Sanity check, is this all zeroes? */
-	if (memchr_inv(data, 0x00, 13)) {
+	if (memchr_inv(data, 0x00, 13) == NULL) {
 		if (!(data[13] & BIT(7)))
 			dev_warn(yas5xx->dev, "calibration is blank!\n");
 	}