usb: xhci: define port register names and use them instead of magic numbers

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index df5e881..31ce422 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3911,7 +3911,7 @@
 	 * Check device's USB 2.0 extension descriptor to determine whether
 	 * HIRD or BESL shoule be used. See USB2.0 LPM errata.
 	 */
-	pm_addr = port_array[port_num] + 1;
+	pm_addr = port_array[port_num] + PORTPMSC;
 	hird = xhci_calculate_hird_besl(xhci, udev);
 	temp = PORT_L1DS(udev->slot_id) | PORT_HIRD(hird);
 	xhci_writel(xhci, temp, pm_addr);
@@ -4009,7 +4009,7 @@
 
 	port_array = xhci->usb2_ports;
 	port_num = udev->portnum - 1;
-	pm_addr = port_array[port_num] + 1;
+	pm_addr = port_array[port_num] + PORTPMSC;
 	temp = xhci_readl(xhci, pm_addr);
 
 	xhci_dbg(xhci, "%s port %d USB2 hardware LPM\n",