drm/radeon/kms: add missing vddci setting on NI+

Need to add vddci setting to pm init as well as
resume.  Fixes hangs on load on some boards.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=38754



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>