drm/radeon/dpm: rework auto performance level enable

Calling force_performance_level() from set_power_state()
doesn't work on some asics because the current power
state pointer has not been properly updated at that point.
Move the calls to force_performance_level() out of the
asic specific set_power_state() functions and into
the main power state sequence.

Fixes dpm resume on SI.

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