net/netvsc: handle Rx packets during multi-channel setup

net/netvsc: handle Rx packets during multi-channel setup

It is possible for a packet to arrive during the configuration
process when setting up multiple queue mode. This would cause
configure to fail; fix by just ignoring receive packets while
waiting for control commands.

Use the receive ring lock to avoid possible races between
oddly behaved applications doing rx_burst and control operations
concurrently.

Fixes: 4e9c73e96e83 ("net/netvsc: add Hyper-V network device")
Cc: stable@dpdk.org
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>