amdtemp(4): Add support for Family 15h, Model >=60h

Family 15h is a bit of an oddball. Early models used the same temperature
register and spec (mostly[1]) as earlier CPU families.

Model 60h-6Fh and 70-7Fh use something more like Family 17h's Service
Management Network, communicating with it in a similar fashion. To support
them, add support for their version of SMU indirection to amdsmn(4) and use
it in amdtemp(4) on these models.

While here, clarify some of the deviceid macros in amdtemp(4) that were
added with arbitrary, incorrect family numbers, and remove ones that were
not used. Additionally, clarify intent and condition of heterogenous
multi-socket system detection.

[1]: 15h adds the "adjust range by -49°C if a certain condition is met,"
which previous families did not have.

Reported by: D. C. <tjoard AT gmail.com>
PR: 234657
Tested by: D. C. <tjoard AT gmail.com>