KVM: Require the PCI subsystem

PCI device assignment makes calls to pci code, so require it to be built
into the kernel.

Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/x86/kvm/Kconfig

@@ -20,6 +20,8 @@ if VIRTUALIZATION
 config KVM
 	tristate "Kernel-based Virtual Machine (KVM) support"
 	depends on HAVE_KVM
+	# for device assignment:
+	depends on PCI
 	select PREEMPT_NOTIFIERS
 	select MMU_NOTIFIER
 	select ANON_INODES