drm/i915/cfl: Fix Workarounds.

During the review of Coffee Lake workarounds Mika pointed out
that WaDisableKillLogic and GEN9_DISABLE_OCL_OOB_SUPPRESS_LOGIC
should be removed from CFL and with that I should carry the rv-b.

However when doing the v2 I removed another Workaround that should
remain because although not mentioned by spec the history of hangs
around it advocates on its favor.

On some follow-up patches I continued operating on the wrong
workardound, but Ville noticed that, so here is the fix for the
current CFL code that is upstream already.

Fixes: 46c26662 ("drm/i915/cfl: Introduce Coffee Lake workarounds.")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>