net/i40e: fix port segmentation fault when restart

net/i40e: fix port segmentation fault when restart

This patch will go into the process of clear all queue region
related configuration when dev stop even if there is no queue region
command before, so this is a bug, it may cause error. So add code
to check if there is queue configuration exist when flush queue
region config and remove this process when device stop. Queue region
clear only do when device initialization or PMD get flush command.

Fixes: 7cbecc2f7424 ("net/i40e: support queue region set and flush")
Cc: stable@dpdk.org
Signed-off-by: Wei Zhao <wei.zhao1@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>