iio: trigger: drop generic interrupt trigger.

iio: trigger: drop generic interrupt trigger.

There is no way to bind to this driver from firmware and no explicit
platform device creation calls exist in mainline.

As such it is dead code. So drop it rather than potentially wasting time
modernizing it (see #1)

Link: https://lore.kernel.org/all/20260511063229.1433-1-sozdayvek@gmail.com/
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>