i40e: keep SR-IOV enabled in the case that RSS, VMDQ, FD_SB and DCB are disabled

Modify the logic in i40e_determine_queue_usage() so that
SR-IOV doesn't get turned off unnecessarily.

Change-ID: I86ca304fa9f742a50e9ea831b887f358a6a9d53d
Signed-off-by: Frank Zhang <frank_1.zhang@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --cc drivers/net/ethernet/intel/i40e/i40e_main.c
Simple merge