iio: adc: Add PM7325 PMIC7 ADC bindings

Add the defines for the ADC channels found on the PM7325. The list is
taken from downstream msm-5.4 and adjusted for mainline.

Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20231013-fp5-thermals-v1-1-f14df01922e6@fairphone.com


Signed-off-by: Bjorn Andersson <andersson@kernel.org>