iio: adc: adi-axi-adc: add axi_adc_num_lanes_set

iio: adc: adi-axi-adc: add axi_adc_num_lanes_set

Assign num_lanes_set in the adi_axi_adc_ops to axi_adc_num_lanes_set()
to support setting number of lanes used by AXI ADC. This operation is
included in the generic structure because the number of lanes is a
configurable parameter of the generic AXI ADC IP core, not specific to
a device.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Ioana Risteiu <Ioana.Risteiu@analog.com>
Link: https://patch.msgid.link/20250825221355.6214-2-Ioana.Risteiu@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>