drm/i915: add LynxPoint-LP PCH ID

[pzanoni: rebase, print it's an LP PCH]
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -401,6 +401,7 @@ MODULE_DEVICE_TABLE(pci, pciidlist);
 #define INTEL_PCH_CPT_DEVICE_ID_TYPE	0x1c00
 #define INTEL_PCH_PPT_DEVICE_ID_TYPE	0x1e00
 #define INTEL_PCH_LPT_DEVICE_ID_TYPE	0x8c00
+#define INTEL_PCH_LPT_LP_DEVICE_ID_TYPE	0x9c00
 
 void intel_detect_pch(struct drm_device *dev)
 {
@@ -440,6 +441,11 @@ void intel_detect_pch(struct drm_device *dev)
 				dev_priv->num_pch_pll = 0;
 				DRM_DEBUG_KMS("Found LynxPoint PCH\n");
 				WARN_ON(!IS_HASWELL(dev));
+			} else if (id == INTEL_PCH_LPT_LP_DEVICE_ID_TYPE) {
+				dev_priv->pch_type = PCH_LPT;
+				dev_priv->num_pch_pll = 0;
+				DRM_DEBUG_KMS("Found LynxPoint LP PCH\n");
+				WARN_ON(!IS_HASWELL(dev));
 			}
 			BUG_ON(dev_priv->num_pch_pll > I915_NUM_PLLS);
 		}