virtio-net: consistently save parameters for per-queue

When using .set_coalesce interface to set all queue coalescing
parameters, we need to update both per-queue and global save values.

Fixes: 394bd877

 ("virtio_net: support per queue interrupt coalesce command")
Cc: Gavin Li <gavinl@nvidia.com>
Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>