staging:iio: Add missing MODULE_DEVICE_TABLE and MODULE_ALIAS

Quite a few iio drivers provide no MODULE_DEVICE_TABLE or MODULE_ALIAS or only
provide a MODULE_ALIAS while they have support for multiple device ids. This
prevents auto module loading from working correctly.

This patch fixes it by adding the missing MODULE_DEVICE_TABLEs and
MODULE_ALIAS'.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>