KVM: Move device assignment logic to common code

To share with other archs, this patch moves device assignment
logic to common parts.

Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 4269be1..9acf34a 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -383,7 +383,9 @@
 #define KVM_CAP_MP_STATE 14
 #define KVM_CAP_COALESCED_MMIO 15
 #define KVM_CAP_SYNC_MMU 16  /* Changes to host mmap are reflected in guest */
+#ifdef CONFIG_X86
 #define KVM_CAP_DEVICE_ASSIGNMENT 17
+#endif
 #define KVM_CAP_IOMMU 18
 
 /*