Array type vmstate has the VMStateField with `num` equals its length.

When the varray vmstate is built based a array type, the `num` field
should be cleaned to 0, because varray uses `num_offset` instead of
`num` to store elements number information.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 rust/qemu-api/src/vmstate.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/vmstate.rs
index 3f95d4825149..e877ee5e391d 100644
--- a/rust/qemu-api/src/vmstate.rs
+++ b/rust/qemu-api/src/vmstate.rs
@@ -275,6 +275,7 @@ pub const fn with_varray_flag<T: VMState>(mut self, flag: VMStateFlags) -> VMSta
         assert!((self.flags.0 & VMStateFlags::VMS_ARRAY.0) != 0);
         self.flags = VMStateFlags(self.flags.0 & !VMStateFlags::VMS_ARRAY.0);
         self.flags = VMStateFlags(self.flags.0 | flag.0);
+        self.num = 0; // varray uses num_offset instead of num.
         self
     }
 
-- 
2.34.1