Moved NET_BUFFERS_SIZE to network/defs.asm

- Changing this value requires changing the routine NET_Buffer_Locate
  so its best to keep both in one module.
- Redefining it in the individual devices doesn't change the code in
  NET_Buffer_Locate

avr/modules/network/defs.asm

@@ -9,7 +9,10 @@
 
 
 ; defs
-.equ NET_MSGNUMINBUF_SIZE               =  4 ; max buffer nums in ringbuffer (global incoming)
+
+.equ NET_BUFFERS_SIZE                   = 32 ; CAVE: need to adapt routine NET_Buffer_Locate when changing this value!!
+
+.equ NET_MSGNUMINBUF_SIZE               =  6 ; max buffer nums in ringbuffer (global incoming)
 
 .equ NET_IFACE_OUTMSGBUF_SIZE           =  4 ; max buffer nums in ringbuffer (per interface outbound)