VSI is being dereferenced before the VSI null check; if VSI is
null we end up with a null pointer dereference. Fix this by
performing VSI deference after the VSI null check. Also remove
the need for using adapter by using vsi->back->cinst.
Detected by CoverityScan, CID#1419696, CID#1419697
("Dereference before null check")
Fixes: ed0e894de7 ("i40evf: add client interface")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>