xen: pvhvm: make it clearer that XEN_UNPLUG_* define bits in a bitfield

by defining in terms of (1<<N).

XEN_UNPLUG_UNNECESSARY and XEN_UNPLUG_NEVER are only used within the
kernel and are not defined as a bit on the unplug IO port. Therefore
use a bit which is outside the potentially valid range of the 16 bit
IO port.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>

include/xen/platform_pci.h

@@ -16,12 +16,15 @@
 #define XEN_IOPORT_PROTOVER	(XEN_IOPORT_BASE + 2) /* 1 byte access (R) */
 #define XEN_IOPORT_PRODNUM	(XEN_IOPORT_BASE + 2) /* 2 byte access (W) */
 
-#define XEN_UNPLUG_ALL_IDE_DISKS 1
-#define XEN_UNPLUG_ALL_NICS 2
-#define XEN_UNPLUG_AUX_IDE_DISKS 4
-#define XEN_UNPLUG_ALL 7
-#define XEN_UNPLUG_UNNECESSARY 8
-#define XEN_UNPLUG_NEVER 16
+#define XEN_UNPLUG_ALL_IDE_DISKS	(1<<0)
+#define XEN_UNPLUG_ALL_NICS		(1<<1)
+#define XEN_UNPLUG_AUX_IDE_DISKS	(1<<2)
+#define XEN_UNPLUG_ALL			(XEN_UNPLUG_ALL_IDE_DISKS|\
+					 XEN_UNPLUG_ALL_NICS|\
+					 XEN_UNPLUG_AUX_IDE_DISKS)
+
+#define XEN_UNPLUG_UNNECESSARY 		(1<<16)
+#define XEN_UNPLUG_NEVER	 		(1<<17)
 
 static inline int xen_must_unplug_nics(void) {
 #if (defined(CONFIG_XEN_NETDEV_FRONTEND) || \