bnx2x: Fix vxlan endianity issue

Commit f34fa14c

 ("bnx2x: Add vxlan RSS support") has introduced an
endianity issue when passing the vxlan UDP port to the HW.

Reported-by:  <fengguang.wu@intel.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>