iio: adc: ad7887: Demote seemingly unintentional kerneldoc header
This is the only use of function related kerneldoc in the sourcefile
and no descriptions are provided.
Fixes the following W=1 kernel build warning(s):
drivers/iio/adc/ad7887.c:119: warning: Function parameter or member 'irq' not described in 'ad7887_trigger_handler'
drivers/iio/adc/ad7887.c:119: warning: Function parameter or member 'p' not described in 'ad7887_trigger_handler'
Cc: Michael Hennerich <Michael.Hennerich@analog.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>