net: context: Go back to LISTEN state when receiving RST

In LISTEN state ignore a TCP RST. In SYN RCVD state, reset TCP
connection state to LISTEN when a valid RST segment is received. In all
other states close the connection - except that these other states will
not be handled in tcp_syn_rcvd() function.

Jira: ZEP-2279

Signed-off-by: Patrik Flykt <patrik.flykt@intel.com>