zoul: Make it possible to override COFFEE_CONF_SIZE
zoul: Make it possible to override COFFEE_CONF_SIZE

The projects need to be able to override it with project-conf.h.

Signed-off-by: Benoît Thébaudeau <b3efeb72fa9d3102885911404c5fbece843f6c8f@gmail.com>

arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,arurke/contiki,MohamedSeliem/contiki,arurke/contiki,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,arurke/contiki,MohamedSeliem/contiki,arurke/contiki,arurke/contiki