ixgbe: disable LLI for FCoE

Disable LLI for FCoE since regular interrupt
and their moderation rate works slightly better
for FCoE also.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>