hwmon: fix dme1737 temp fault attribute

Fix temp?_fault attribute. The temp was incorrectly compared against
0x0800 rather than 0x8000. Only the upper 8 bits are compared as the
datasheet doesn't specify what happens to the lower bits in case of a
diode fault.

Signed-off-by: Juerg Haefliger <juergh at gmail.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>