iio: adc: Kconfig change description for Allwinner GPADC

This patch adds SoCs names to Allwinner GPADC description to
make it more informative.

Signed-off-by: Maksim Kiselev <bigunclemax@gmail.com>
Link: https://lore.kernel.org/r/20230619154252.3951913-2-bigunclemax@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>