hwmon: (scpi-hwmon) shows the negative temperature properly

hwmon: (scpi-hwmon) shows the negative temperature properly

[ Upstream commit 78d13552346289bad4a9bf8eabb5eec5e5a321a5 ]

The scpi hwmon shows the sub-zero temperature in an unsigned integer,
which would confuse the users when the machine works in low temperature
environment. This shows the sub-zero temperature in an signed value and
users can get it properly from sensors.

Signed-off-by: Riwen Lu <luriwen@kylinos.cn>
Tested-by: Xin Chen <chenxin@kylinos.cn>
Link: https://lore.kernel.org/r/20210604030959.736379-1-luriwen@kylinos.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>