doc: Make sysfs-bus-iio doc more exact

A few IIC channel descriptions explained used units as:
data is in foo "that can be processed into an" [unit] value. The "can be
processed into" is quite broad statement as it does not really explain
what this processing means. This makes units pretty much useless.

After discussion with Jonathan, it seems the units for these channels
should also be well-defined as for all other channels. The processing
means the standard scale and offset application that is used throughout
the IIO. Let's make it more obvious by stating that the units are [unit]
after scale ane offset are applied.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/41eafb0caa510cddf650cf5ff940639a184f3005.1677331779.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/ABI/testing/sysfs-bus-iio

@@ -1807,8 +1807,8 @@ What:		/sys/bus/iio/devices/iio:deviceX/out_resistanceX_raw
 KernelVersion:	4.3
 Contact:	linux-iio@vger.kernel.org
 Description:
-		Raw (unscaled no offset etc.) resistance reading that can be processed
-		into an ohm value.
+		Raw (unscaled no offset etc.) resistance reading.
+		Units after application of scale and offset are ohms.
 
 What:		/sys/bus/iio/devices/iio:deviceX/heater_enable
 KernelVersion:	4.1.0
@@ -1894,8 +1894,9 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_electricalconductivity_raw
 KernelVersion:	4.8
 Contact:	linux-iio@vger.kernel.org
 Description:
-		Raw (unscaled no offset etc.) electric conductivity reading that
-		can be processed to siemens per meter.
+		Raw (unscaled no offset etc.) electric conductivity reading.
+		Units after application of scale and offset are siemens per
+		meter.
 
 What:		/sys/bus/iio/devices/iio:deviceX/in_countY_raw
 KernelVersion:	4.10
@@ -1951,8 +1952,8 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_phaseY_raw
 KernelVersion:	4.18
 Contact:	linux-iio@vger.kernel.org
 Description:
-		Raw (unscaled) phase difference reading from channel Y
-		that can be processed to radians.
+		Raw (unscaled) phase difference reading from channel Y.
+		Units after application of scale and offset are radians.
 
 What:		/sys/bus/iio/devices/iio:deviceX/in_massconcentration_pm1_input
 What:		/sys/bus/iio/devices/iio:deviceX/in_massconcentrationY_pm1_input