drm/radeon/dpm: add bapm callback for trinity

This adds the enable_bapm callback for trinity.

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

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/trinity_dpm.c
Simple merge

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