ixgbevf: Do not forward LLDP type frames

The driver should not forward LLDP type frames.  Inspect the ether type and
do not send if it is an LLDP ethertype frame.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>