drm/i915: fix guest virtual PCH detection on non-PCH systems

Virtualized non-PCH systems such as Broxton or Geminilake should use
PCH_NONE to indicate no PCH rather than PCH_NOP. The latter is a
specific case to indicate a PCH system without south display.
Reported-by: Colin Xu <Colin.Xu@intel.com>
Cc: Colin Xu <Colin.Xu@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Colin Xu <Colin.Xu@intel.com>
Reviewed-by: Colin Xu <Colin.Xu@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180608123330.31003-2-jani.nikula@intel.com

drivers/gpu/drm/i915/i915_drv.c

@@ -289,7 +289,7 @@ static void intel_detect_pch(struct drm_i915_private *dev_priv)
 				if (WARN_ON(pch_type == PCH_NONE))
 					pch_type = PCH_NOP;
 			} else {
-				pch_type = PCH_NOP;
+				pch_type = PCH_NONE;
 			}
 			dev_priv->pch_type = pch_type;
 			dev_priv->pch_id = id;