For uniquely identifying the vadc channels, label property has to be used.
The initial commit adding vadc support assumed that the driver will use the
unit address along with the node name to identify the channels. But this
assumption is now broken by,
commit 701c875a ("iio: adc: qcom-spmi-adc5: Fix the channel name") that
stripped unit address from channel names. This results in probe failure of
the vadc driver:

[    8.380370] iio iio:device0: tried to double register : in_temp_pmic-die-temp_input
[    8.380383] qcom-spmi-adc5 c440000.spmi:pmic@0:adc@3100: Failed to register sysfs interfaces
[    8.380386] qcom-spmi-adc5: probe of c440000.spmi:pmic@0:adc@3100 failed with error -16

Hence, let's get rid of the assumption about drivers and rely on label
property to uniquely identify the channels.

The labels are derived from the schematics for each PMIC. For internal adc
channels such as die and xo, the PMIC names are used as a prefix.

Fixes: 7c015134 ("arm64: dts: qcom: sc8280xp-x13s: Add PM8280_{1/2} ADC_TM5 channels")
Fixes: 9d41cd17 ("arm64: dts: qcom: sc8280xp-x13s: Add PMR735A VADC channel")
Fixes: 3375151a ("arm64: dts: qcom: sc8280xp-x13s: Add PM8280_{1/2} VADC channels")
Fixes: 9a6b3042 ("arm64: dts: qcom: sc8280xp-x13s: Add PMK8280 VADC channels")
Reported-by: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230211052415.14581-1-manivannan.sadhasivam@linaro.org