Add initial swSMU support for smu 14 series ASIC.

v2: squash in build fixes and updates (Li Ma)
    fix warnings (Alex)
v3: squash in updates (Alex)
v4: squash in updates (Alex)
v5: squash in avg/current power updates (Alex)
Signed-off-by: Li Ma <li.ma@amd.com>
Signed-off-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>