ice: fix the divide by zero issue

Static analysis flagged a potential divide by zero error because
vsi->num_rxq can become zero in certain condition and it is used as
divisor.

Signed-off-by: Kiran Patil <kiran.patil@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>