iio: adis16400: Fix an error code in adis16400_initial_setup()

This is to silence a new Smatch warning:

    drivers/iio/imu/adis16400.c:492 adis16400_initial_setup()
    warn: sscanf doesn't return error codes

If the condition "if (st->variant->flags & ADIS16400_HAS_SLOW_MODE) {"
is false then we return 1 instead of returning 0 and probe will fail.

Fixes: 72a868b3 ("iio: imu: check sscanf return value")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YCwgFb3JVG6qrlQ+@mwanda


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>