iio: adc: PAC1934: fix accessing out of bounds array index
In the Linux kernel, the following vulnerability has been resolved:

iio: adc: PAC1934: fix accessing out of bounds array index

Fix accessing out of bounds array index for average
current and voltage measurements. The device itself has
only 4 channels, but in sysfs there are "fake"
channels for the average voltages and currents too.