ixgbe: fix bounds checking in ixgbe_setup_tc for 82598

This patch resolves an issue where users were not able to dynamically
set number of queues for 82598 via ethtool -L

Reported-by: Tal Abudi <talabudi@gmail.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>