net/i40e: fix request queue in VF

net/i40e: fix request queue in VF

When the VF configuration is larger than the number of queues reserved
by PF, VF sends the request queue command through admin queue. When PF
received this command, it may reset the VF and send a notification
before resetting. If this notification is read by the timed task alarm,
Task request queue will lost notification. This patch prevents two
tasks from running simultaneously.

Fixes: ee653bd80044 ("net/i40e: determine number of queues per VF at run time")
Cc: stable@dpdk.org
Signed-off-by: Tao Zhu <taox.zhu@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>