iio: adc: cf_axi_adc_core: simplify axiadc_dco_calibrate()

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
iio: Add callback to check whether a scan mask is valid

This is useful for cases where the number of valid scan masks grows
exponentially, but it is rather easy to check whether a mask is valid or not
programmatically.

An example of such a case is a device with multiple ADCs where each ADC has a
upstream MUX, which allows to select from a number of physical channels.

  +-------+   +-------+
  |       |   |       | --- Channel 1
  | ADC 1 |---| MUX 1 | ---   ...
  |       |   |       | --- Channel M
  +-------+   +-------+

     .            .            .
     .            .            .
     .            .            .

  +-------+   +-------+
  |       |   |       | --- Channel M * N + 1
  | ADC N |---| MUX N | ---       ...
  |       |   |       | --- Channel M * N + M
  +-------+   +-------+

The number of necessary scan masks for this case is (M+1)**N - 1, on the other
hand it is easy to check whether subsets for each ADC of the scanmask have only
one bit set.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
microblaze: platform: Update ADI device trees

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
iio: frequency: fix bug in FRAME retry count handling

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
iio: adc: cf_axi_adc_core: axiadc_dco_calibrate() AD9265 doesn't feature DCO enable

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
iio: adc: cf_axi_adc_core: Complete support for User Logic HDL extensions

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>