drm/radeon/kms: add dpm support for btc (v3)

This adds dpm support for btc asics.  This includes:
- clockgating
- dynamic engine clock scaling
- dynamic memory clock scaling
- dynamic voltage scaling
- dynamic pcie gen1/gen2 switching (requires additional acpi support)

Set radeon.dpm=1 to enable.

v2: reduce stack usage
v3: attempt to fix state enable

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

diff --cc drivers/gpu/drm/radeon/Makefile
Simple merge

diff --cc drivers/gpu/drm/radeon/btc_dpm.c
Simple merge

diff --cc drivers/gpu/drm/radeon/btc_dpm.h
Simple merge

diff --cc drivers/gpu/drm/radeon/btcd.h
Simple merge

diff --cc drivers/gpu/drm/radeon/ni.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_asic.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_asic.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_pm.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_ucode.h
Simple merge

diff --cc drivers/gpu/drm/radeon/rv770_smc.c
Simple merge