net/i40e: fix VSI removing when releasing

net/i40e: fix VSI removing when releasing

VSI structure needs to be removed from TAILQ list when releasing.
But for the child VSI it will be removed again after the structure
is freed. It will cause core dump when the DPDK i40e using as PF
host driver.

This patch fixes it to only remove child VSI from TAILQ before
send adminq command to remove it from hardware.

Fixes: 4861cde46116 ("i40e: new poll mode driver")
Fixes: 440499cf5376 ("net/i40e: support floating VEB")

Signed-off-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>