w1: fix w1_ds2438 documentation

The previous documentation was wrongly stating about the order
of magnitude of CONVERT_V result files contents (vad, vdd).
This commit is correcting this.
Reported-by: NAdam Stolarczyk <adam@stolarczyk.net.pl>
Signed-off-by: NMariusz Bialonczyk <manio@skyboo.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/w1/slaves/w1_ds2438

@@ -60,4 +60,4 @@ vad: general purpose A/D input (VAD)
 vdd: battery input (VDD)
 
 After the voltage conversion the value is returned as decimal ASCII.
-Note: The value is in mV, so to get a volts the value has to be divided by 10.
+Note: To get a volts the value has to be divided by 100.