staging: iio: accel: adis16240: Drop driver for this impact sensor

Whilst an interesting part, no one has done significant work on this
driver since 2019.  The recent changes are all as a result of adis library
improvements having to incorporate this device.

https://www.analog.com/en/products/adis16240.html now lists this part
as obsolete so the chances of anyone working on it are likely to be greatly
reduced.

So drop it.  We can always bring it back if anyone does have interest in
this device and is willing to invest the time to make it suitable for a
staging graduation.  How to handle the hardware triggered short bursts
of capture has never been resolved and is a somewhat challenging ABI design
problem.

Cc: Nuno Sa <nuno.sa@analog.com>
Cc: Rodrigo Carvalho <rodrigorsdc@gmail.com>
Link: https://patch.msgid.link/20250222152021.1039675-1-jic23@kernel.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>