samples: net: openthread: border_router: Enable IPv4 to IPv6 mapping

Updated border router configuration to enable IPv4 to IPv6 address
mapping feature

Signed-off-by: Cristian Bulacu <[email protected]>

Author: Cristib05

samples/net/openthread/border_router/prj.conf

@@ -5,6 +5,7 @@ CONFIG_NET_UDP=y
 CONFIG_NET_TCP=y
 CONFIG_NET_IPV6=y
 CONFIG_NET_IPV4=y
+CONFIG_NET_IPV4_MAPPING_TO_IPV6=y
 CONFIG_NET_SOCKETS=y
 CONFIG_NET_DHCPV4=y
 CONFIG_NET_MGMT_EVENT=y