ibmveth: Remove dead frag processing code

Removes dead frag processing code from ibmveth. Since NETIF_F_SG was
not set, this code was never executed. Also, since the ibmveth
interface can only handle 6 fragments, core networking code would need
to be modified in order to efficiently enable this support.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>