The TSC part allows to specify the input lines. The IIO part assumes
that it usues always the last few, that means if IIO has adc-channels
set to 2 it will use channel 6 and 7. However it might make sense to use
only 6.
This patch changes the device property (which was introduced recently
and was never in an official release) in a way that the user can specify
which of the AIN lines should be used. In Addition to this, the name is
now AINx where x is the channel number i.e. for AIN6 we would have 6.
Prior this, it always started counting at 0 which is confusing. In
addition to this, it also checks for correct step number during reading
and does not rely on proper FIFO depth.
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>