enable/disable GPIO clock per pin, not at platform level

Summarizing this information in the platform may be more efficient but
also makes the code highly non-modular.
enable SPI clock per device, not at platform level
Contiki/gpio.c: only use banks that are actually available
remove no longer needed enable_spi_clocks

We now do all the clock initialization baseds on the specific resources we
use and therefore no longer need such a central setup function.
derive IRQ_HANDLER from the pin being used
Contiki/extint.c: merge and abstract external interrupt setup and configuration
merge rf230-hal-gpio.c and rf230-hap-spi.c

All platform dependencies have now been pushed out of the HAL.
merge rf230bb.h back into rf230-hal.c

Since we now have only one HAL there's nothing that needs sharing via a
header.
WM09/Makefile: we no longer use -DDEV9 (it's implied by platform.h)
SPI API: add weak abstraction for SPI device

This is more a placeholder than a proper abstraction for now. It should
include an interface type specific initialization (e.g., hardware SPI
device or GPIOs) and also include the nSEL pin.
GPIO API: assign GPIO pin IDs and use those for most functions

As opposed to playing macro tricks with PORT_xxx and BIT_xxx. This
vaguely mimicks the Linux GPIO API.
various build fixes for spi-gpio
WM09/Makefile: we can now also support DEV9 with the bit-banging SPI driver
E407: macros ODEV_GPIO and ODEV_SPI did the same; merge and call "ODEV"
rename spi-hw.* to spi-stm32.* (to avoid future name clashes)
make parameter to SPI functions platform-independent
move setting of most SPI device parameters to platform.h
WM09/platform.h: switch SPI initialization based on selected driver
Merge commit 'cece21dda779ae9d519994f340207c3bb6d85747'

Fell off the "master" branch :-(

Conflicts:
	FreeRTOS/Demo/E407/platform.h
	FreeRTOS/Demo/Shared/Contiki/gpio.c
	FreeRTOS/Demo/Shared/Contiki/gpio.h
	FreeRTOS/Demo/Shared/Contiki/rf230-hal-gpio.c
	FreeRTOS/Demo/Shared/Contiki/rf230-hal.c
	FreeRTOS/Demo/Shared/Contiki/spi-gpio.c
	FreeRTOS/Demo/Shared/Contiki/spi-hw.c
	FreeRTOS/Demo/WM09/platform.h