iio: core: Clean up device correctly on viio_trigger_alloc() failure

iio: core: Clean up device correctly on viio_trigger_alloc() failure

Move device_initialize() after all error paths in viio_trigger_alloc().
Previously, put_device() should have been called on all error paths after
device_initialize(), but that was not done.

Rather than adding put_device(), move device_initialize() to avoid
needing to unwind it on error.

In addition move trig->dev initialization to just before device_initialize()
to related code together.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>