drm/i915/chv: Populate total EU count on Cherryview

Starting with Cherryview, devices may have a varying number of EU for
a given ID due to creative fusing. Punit support different frequency for
different fuse data. We use this patch to help get total eu enabled and
read the right offset to get RP0

Based upon a patch from Jeff, but reworked to only store eu_total and
avoid sending info to userspace

v2: Format register definitions (Jani)

Signed-off-by: Deepak S <deepak.s@linux.intel.com>
Acked-by: Jeff McGee <jeff.mcgee@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>