Intel xhci: Add PCI id for Panther Point xHCI host.

This adds the PCI ID for the xHCI (USB 3.0) host controller in the Intel
Panther Point chipset.  It will be used by both the EHCI and xHCI driver
in the following patches.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

include/linux/pci_ids.h

@@ -2483,6 +2483,7 @@
 #define PCI_DEVICE_ID_INTEL_COUGARPOINT_LPC_MAX	0x1c5f
 #define PCI_DEVICE_ID_INTEL_PATSBURG_LPC_0	0x1d40
 #define PCI_DEVICE_ID_INTEL_PATSBURG_LPC_1	0x1d41
+#define PCI_DEVICE_ID_INTEL_PANTHERPOINT_XHCI	0x1e31
 #define PCI_DEVICE_ID_INTEL_PANTHERPOINT_LPC_MIN	0x1e40
 #define PCI_DEVICE_ID_INTEL_PANTHERPOINT_LPC_MAX	0x1e5f
 #define PCI_DEVICE_ID_INTEL_DH89XXCC_LPC_MIN	0x2310