drm/i915: Use HAS_PCH_CPT() everywhere

We have a few cases comparing pch_type directly. Let's just replace
them with HAS_PCH_CPT() since CPT/PPT is what they're looking for.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170620130310.13245-2-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>