Allow an alternate sysfs file name for chip features. This is
needed to provide backward compatibility when changes are made
to the sysfs interface (policy change or driver fix).
The first item for which this is needed is VID files. The name
we chose, in0_ref, is bad (because motherboard manufacturers can
use any input for VCore, regardless of the recommendations.
Thus, the new name cpu0_vid is better. Drivers will be updated