platform/x86: dell-ddv: Fix temperature scaling

platform/x86: dell-ddv: Fix temperature scaling

After using the built-in UEFI hardware diagnostics to compare
the measured battery temperature, i noticed that the temperature
is actually expressed in tenth degree kelvin, similar to the
SBS-Data standard. For example, a value of 2992 is displayed as
26 degrees celsius.
Fix the scaling so that the correct values are being displayed.

Tested on a Dell Inspiron 3505.

Fixes: a77272c16041 ("platform/x86: dell: Add new dell-wmi-ddv driver")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20230218115318.20662-2-W_Armin@gmx.de
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>