MFC 308005: Add powerd(8) support for several families of AMD CPUs.

MFC 308005: Add powerd(8) support for several families of AMD CPUs.

Use the same logic to calculate the nominal CPU frequency from the P-state
MSRs on family 0x12, 0x15, and 0x16 CPUs as is used for family 0x10.
Family 0x14 was included in the original patch in the PR but I left that
out as the BIOS writer's guide for family 0x14 CPUs show a different layout
for the relevant MSR and include a different formulate for calculating the
frequency.

While here, simplify a few expressions and print out the family of
unsupported CPUs in hex rather than decimal.

PR:		212020

git-svn-id: svn://svn.freebsd.org/base/stable/10@309443 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f