drm/radeon/dpm: use the driver state for dpm debugfs

For btc and newer, we may modify the power state depending
on the circumstances. Use the modified state rather than
the base state.

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

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>