vhost-vdpa :Fix Coverity CID 1430270 / CID 1420267

In the function vhost_vdpa_dma_map/unmap, The struct msg was not initialized all its fields.

Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20200710064642.24505-1-lulu@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/vhost-vdpa.c

@@ -37,7 +37,7 @@ static bool vhost_vdpa_listener_skipped_section(MemoryRegionSection *section)
 static int vhost_vdpa_dma_map(struct vhost_vdpa *v, hwaddr iova, hwaddr size,
                               void *vaddr, bool readonly)
 {
-    struct vhost_msg_v2 msg;
+    struct vhost_msg_v2 msg = {};
     int fd = v->device_fd;
     int ret = 0;
 
@@ -60,7 +60,7 @@ static int vhost_vdpa_dma_map(struct vhost_vdpa *v, hwaddr iova, hwaddr size,
 static int vhost_vdpa_dma_unmap(struct vhost_vdpa *v, hwaddr iova,
                                 hwaddr size)
 {
-    struct vhost_msg_v2 msg;
+    struct vhost_msg_v2 msg = {};
     int fd = v->device_fd;
     int ret = 0;