cxgb4: fix 64-bit division on i386

Fix following compile error on i386 architecture.

ERROR: "__udivdi3" [drivers/net/ethernet/chelsio/cxgb4/cxgb4.ko] undefined!

Fixes: 0e395b3c

 ("cxgb4: add FLOWC based QoS offload")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>