Explain disadvantages of building pciback as a module in Kconfig help.

Fix a module-loading bug in pciback.

From: Jan Beulich
Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/drivers/xen/Kconfig

@@ -35,7 +35,9 @@ config XEN_PCIDEV_BACKEND
 	default XEN_PRIVILEGED_GUEST
 	help
 	  The PCI device backend driver allows the kernel to export arbitrary
-	  PCI devices to other guests.
+	  PCI devices to other guests. If you select this to be a module, you
+	  will need to make sure no other driver has bound to the device(s)
+	  you want to make visible to other guests.
 
 choice
 	prompt "PCI Backend Mode"

linux-2.6-xen-sparse/drivers/xen/pciback/pci_stub.c

@@ -378,7 +378,7 @@ fs_initcall(pcistub_init);
 
 static int __init pciback_init(void)
 {
-#ifndef MODULE
+#ifdef MODULE
 	int err;
 
 	err = pcistub_init();