drm/i915/cnl: Also need power well sanitize.

The workaround added in
commit c6782b76 ("drm/i915/gen9: Reset secondary power well
equests left on by DMC/KVMR")
needs to be applied on Cannonlake as well.

So let's assume any platform using this power well setup
will also need and let's just go ahead and remove if condition.

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1496781040-20888-11-git-send-email-rodrigo.vivi@intel.com