i40e: trivial: remove unnecessary local var

Probe routine already has too many locals, just convert one
used for kzalloc into a kcalloc, eliminating the local.

Change-ID: I349049872b71f858cbeb91ad7836e6767fc7b7d1
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Reviewed-by: Anjali Singhai <anjali.singhai@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>