x86/xen: Link platform-pci-unplug.o only if CONFIG_XEN_PVHVM

Instead of using one large #ifdef CONFIG_XEN_PVHVM in
arch/x86/xen/platform-pci-unplug.c add the object file depending on
CONFIG_XEN_PVHVM being set.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: xen-devel@lists.xenproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: akataria@vmware.com
Cc: rusty@rustcorp.com.au
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/20180828074026.820-4-jgross@suse.com

arch/x86/xen/Makefile

@@ -19,11 +19,11 @@ obj-y				+= mmu.o
 obj-y				+= time.o
 obj-y				+= grant-table.o
 obj-y				+= suspend.o
-obj-y				+= platform-pci-unplug.o
 
 obj-$(CONFIG_XEN_PVHVM)		+= enlighten_hvm.o
 obj-$(CONFIG_XEN_PVHVM)		+= mmu_hvm.o
 obj-$(CONFIG_XEN_PVHVM)		+= suspend_hvm.o
+obj-$(CONFIG_XEN_PVHVM)		+= platform-pci-unplug.o
 
 obj-$(CONFIG_XEN_PV)		+= setup.o
 obj-$(CONFIG_XEN_PV)		+= apic.o

arch/x86/xen/platform-pci-unplug.c

@@ -30,7 +30,6 @@
 #define XEN_PLATFORM_ERR_PROTOCOL -2
 #define XEN_PLATFORM_ERR_BLACKLIST -3
 
-#ifdef CONFIG_XEN_PVHVM
 /* store the value of xen_emul_unplug after the unplug is done */
 static int xen_platform_pci_unplug;
 static int xen_emul_unplug;
@@ -214,4 +213,3 @@ static int __init parse_xen_emul_unplug(char *arg)
 	return 0;
 }
 early_param("xen_emul_unplug", parse_xen_emul_unplug);
-#endif