cxgb3: Fix LRO misalignment

The lro manager's frag_align_pad setting was missing,
leading to misaligned access to the skb passed up
to the stack.

Tested-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>