iavf: Fix static code analysis warning

Change min() to min_t() to fix static code analysis warning of possible
overflow.

Signed-off-by: Paul Greenwalt <paul.greenwalt@intel.com>
Signed-off-by: Karen Sornek <karen.sornek@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>