i40e: remove unnecessary qv_info ptr NULL checks

The "qv_info" ptr cannot be NULL when it gets the address of
an element of the flexible array "qvlist_info->qv_info".

Detected using the static analysis tool - Svace.

Signed-off-by: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>