Implementing basic LLDP server, should send port_id message

to each port once every 30 seconds.
* Additionally fixes the on-ward passing of LLDP frames through
the switch

The ports on the case are marked 1-8 so this should reflect that
rather than being 0-based

We can send the hostname as well, this can be dynamically allocated

Let's send the model as the system description as well

Makefile

@@ -83,6 +83,7 @@ SRCS += \
 	rtl837x_pins.c\
 	rtl837x_port.c \
 	rtl837x_stp.c \
+	rtl837x_lldp.c \
 	rtl837x_storm.c
 SRCS += \
 	httpd/httpd.c \