net/vmxnet3: ignore empty segments in reception

net/vmxnet3: ignore empty segments in reception

When several TCP fragments are contained in a packet that is only one mbuf
segment long, vmxnet3 receives an empty segment following first one, that
contains offload information. In current version, this segment is
propagated as is to upper application.
Remove those empty segments directly when receiving buffers, they may
generate unneeded extra processing in the upper application.

Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Acked-by: Yong Wang <yongwang@vmware.com>