adi: cn0540: Re-add calibration procedure

[machschmitt]

Description

CN0540 calibration procedure was removed in February, 2022. However, costumers reported missing that feature in August, 2023. The same commit that removed the calibrate function from CN0540 also added a slightly updated version of the calibrate function to CN0532. Re-introduce the calibration feature to CN0540 on same updated form that is available in CN0532.

Link: https://ez.analog.com/linux-software-drivers/f/q-a/572902/trouble-calibrating-cn0540-using-pyadi-iio?queryID=411c40aa86081da8ea48e1c6bad51858&objectId=82ecfad5-7016-4bd9-b5f2-74ffcddb4450&eztype=Forum%20Thread

Fixes: eaad1fa ("[cn0540] Update calibration routine")

Fixes # (issue)

Type of change

• Bug fix
• New device class interface
• New feature on an existing class
• Breaking change
• Documentation only
• Test or CI only

How has this been tested?

State explicitly whether this was tested against real hardware, an emulated context (iio-emu), or not run. Name the part(s) and the context URI or board used.

• Hardware / emulation:
• Commands run (e.g. python3 -m pytest -k ad4080 --adi-hw-map):
• Result:

Test configuration

• Kernel / libiio version:
• OS:
• FPGA carrier (if applicable):

Documentation

• No documentation change needed
• Updated existing docs under doc/source/
• Added a new device page and linked it from the relevant toctree

Checklist

• invoke precommit passes locally
• All commits are signed off (Signed-off-by: Name <email>)
• No new warnings from the build or doc generation
• Dependent changes in libiio, kernel, or HDL are merged and referenced