E407/Makefile.stm32: combine settings depending on core arch
E407/Makefile.contiki: abstract core arch dependencies
E407/Makefile.contiki (SRC): tweak paths such that they also work from ../WM09/
E407/hal-spi.c: provide abstractions for different SPI hardware layouts
E407/hal-spi.c: add DEV9 configuration
WM09/: build a FreeRTOS-Contiki hybrid that uses atben on DEV9