iio: adc: dln2-adc: zero full struct instead of just the padding

iio: adc: dln2-adc: zero full struct instead of just the padding

Drop a minor optimization of zeroing the padding between data and
timestamp and zero the whole structure. This is done in favor of
simpler code, and in order to drop the usage of the internal private
variable "scan_timestamp" of the struct iio_dev.

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://patch.msgid.link/20241214191421.94172-2-vassilisamir@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>