If max1027_wait_eoc() fails then call iio_device_release_direct_mode()
before returning.

Fixes: a0e83165 ("iio: adc: max1027: Introduce an end of conversion helper")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YsbztVuAXnau2cIZ@kiliSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>