net/i40e: cancel alarm handler at the end of closure

net/i40e: cancel alarm handler at the end of closure

Some operations in i40evf_dev_close like i40evf_dev_promiscuous_disable
still need alarm handler to clear the pending cmd, if alarm handler is
canceled in early stage of i40evf_dev_close,
i40evf_dev_promiscuous_disable will result in failure.

Fixes: 864a800d706d ("net/i40e: remove VF interrupt handler")
Cc: stable@dpdk.org
Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
Acked-by: Beilei Xing <beilei.xing@intel.com>