vmmouse: fix queue_size field initialization

Initialize the field queue_size, dropped by
91c9e09147ba1f3604a3d5d29b4de7702082a33f.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/vmmouse.c b/hw/vmmouse.c
index 11b125c..ab8dbd6 100644
--- a/hw/vmmouse.c
+++ b/hw/vmmouse.c
@@ -253,6 +253,7 @@
     VMMouseState *s = container_of(d, VMMouseState, dev.qdev);
 
     s->status = 0xffff;
+    s->queue_size = VMMOUSE_QUEUE_SIZE;
 }
 
 static int vmmouse_initfn(ISADevice *dev)