net: core: Handle packets when packet sockets are enabled

If CONFIG_NET_SOCKETS_PACKET is enabled, then feed the packet
to net_packet_socket_input() for processing. It will search
for the net_contexts and if proper handler is found, pass
the packet to connection handler.

Signed-off-by: Ravi kumar Veeramally <ravikumar.veeramally@linux.intel.com>