Clear csum_flags after reading data from socket buffer.  Otherwise, if ksocket is connected to an interface-type node somewhere later in the graph (e.g., ng_eiface or ng_iface), the csum_data may be applied to a wrong packet (if we encapsulate Ethernet or IP).
Clear csum_flags after reading data from socket buffer.  Otherwise,
if ksocket is connected to an interface-type node somewhere later
in the graph (e.g., ng_eiface or ng_iface), the csum_data may be
applied to a wrong packet (if we encapsulate Ethernet or IP).

MFC after:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase