On the Xserve G5 we find the LM75 instead of the DS1775. The core
functionality is the same, a difference is that the DS1775 has a better
precision than the LM75. But we do not use it in our setup. Make the
LM75 work the same as the DS1775.

Fix a typo in device_set_desc.

Tested by: Paul Mather <paul at gromit dlib vt edu>

Approved by: nwhitehorn (mentor)