netdev-dpdk: Restore txq/rxq number if initialization fails.

netdev-dpdk: Restore txq/rxq number if initialization fails.

netdev_dpdk_set_multiq() should not set the number of configured rxq
and txq if the driver initialization fails (meaning that the driver
failed to setup the queues).  Otherwise, on a subsequent call to
netdev_dpdk_set_multiq(), the code may believe that the queues have
already been setup and there's no work to be done.

This commit fixes the problem by restoring the old values if
dpdk_eth_dev_init() fails.

Reported-by: Ian Stokes <ian.stokes@intel.com>
Tested-by: Ian Stokes <ian.stokes@intel.com>
Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>