virtio-blk: delete vqs on the error path in realize()

virtio-blk: delete vqs on the error path in realize()

virtio_vqs forgot to free on the error path in realize(). Fix that.

The asan stack:
Direct leak of 14336 byte(s) in 1 object(s) allocated from:
    #0 0x7f58b93fd970 in __interceptor_calloc (/lib64/libasan.so.5+0xef970)
    #1 0x7f58b858249d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5249d)
    #2 0x5562cc627f49 in virtio_add_queue /mnt/sdb/qemu/hw/virtio/virtio.c:2413
    #3 0x5562cc4b524a in virtio_blk_device_realize /mnt/sdb/qemu/hw/block/virtio-blk.c:1202
    #4 0x5562cc613050 in virtio_device_realize /mnt/sdb/qemu/hw/virtio/virtio.c:3615
    #5 0x5562ccb7a568 in device_set_realized /mnt/sdb/qemu/hw/core/qdev.c:891
    #6 0x5562cd39cd45 in property_set_bool /mnt/sdb/qemu/qom/object.c:2238

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20200328005705.29898-2-pannengyuan@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>