KVM: resize kvm_io_range array dynamically

This patch makes the kvm_io_range array can be resized dynamically.

Signed-off-by: Amos Kong <akong@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 665a260..ba9fb4a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -68,10 +68,11 @@
 	struct kvm_io_device *dev;
 };
 
+#define NR_IOBUS_DEVS 300
+
 struct kvm_io_bus {
 	int                   dev_count;
-#define NR_IOBUS_DEVS 300
-	struct kvm_io_range range[NR_IOBUS_DEVS];
+	struct kvm_io_range range[];
 };
 
 enum kvm_bus {