drm/radeon/kms: add dpm support for SI (v7)

This adds dpm support for SI asics.  This includes:
- dynamic engine clock scaling
- dynamic memory clock scaling
- dynamic voltage scaling
- dynamic pcie gen1/gen2/gen3 switching
- power containment
- shader power scaling

Set radeon.dpm=1 to enable.

v2: enable hainan support, rebase
v3: guard acpi stuff
v4: fix 64 bit math
v5: fix 64 bit div harder
v6: fix thermal interrupt check noticed by Jerome
v7: attempt fix state enable

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>