iio: dummy_evgen: remove Excess kernel-doc comments

iio: dummy_evgen: remove Excess kernel-doc comments

Drop kernel-doc comments for struct fields that were removed to
prevent kernel-doc warnings:

iio_dummy_evgen.c:43: warning: Excess struct member 'irq_sim' description in 'iio_dummy_eventgen'
iio_dummy_evgen.c:43: warning: Excess struct member 'base' description in 'iio_dummy_eventgen'

Fixes: 337cbeb2c13e ("genirq/irq_sim: Simplify the API")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20240121055005.20042-1-rdunlap@infradead.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>