drm/radeon/atom: initialize more atom interpretor elements to 0

The ProcessAuxChannel table on some rv635 boards assumes
the divmul members are initialized to 0 otherwise we get
an invalid fb offset since it has a bad mask set when
setting the fb base.  While here initialize all the
atom interpretor elements to 0.

Fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=60639

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
drm: fix 64 bit drm fixed point helpers

Sign bit wasn't handled properly and a small typo.

Thanks to Christian for helping me sort this out.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drm/radeon/dpm: fix calculations in si_calculate_leakage_for_v_and_t_formula

Need to make some slight adjustments for the fixed point math to
work properly.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drm/radeon/dpm: re-enable cac control on SI

Now that the fixed point functions are fixed we
can re-enable cac support.

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