i40e: Prevent overflow due to kzalloc

To prevent the possibility of overflow due multiplication of number and size
use kcalloc instead of kzalloc.

Change-ID: Ibe4d81ed7d9738d3bbe66ee4844ff9be817e8080
Signed-off-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>