[msp430] remove NULL initializers
[platform] replace direct calls to platform.msleep() & platform.get_ticks_from_boot() with wrappers asserting the existence of these methods in the platform
[net] enc28j60: init bank to 255 so that bank is selected on the first register access
[msp430f5529] spi: generalize usci configuration registers
[msp430f5529] gpio: API for setting pin function
[msp430f5529] initialize usci gpios from usci generic code
[msp430f5529] make platform spi max speed and system clock use unsigned long instead of int
[msp430f5529] add system clock fetch function
[msp430f5529] initial SPI support