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: 337cbeb2 ("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.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dummy/iio_dummy_evgen.c

@@ -31,8 +31,6 @@
  * @regs: irq regs we are faking
  * @lock: protect the evgen state
  * @inuse: mask of which irqs are connected
- * @irq_sim: interrupt simulator
- * @base: base of irq range
  * @irq_sim_domain: irq simulator domain
  */
 struct iio_dummy_eventgen {