staging:iio:adc Add IIO_CHAN_INFO_RAW entries to all drivers.

staging:iio:adc Add IIO_CHAN_INFO_RAW entries to all drivers.

Precursor to making value read / write attribute optional.
No processed values for adc's.

Updated to include the spear adc driver (hence introducing a
dependency on the patch that adds that driver).

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