Update contiki upstream
Fix use of obsolete u16/u32 in ocm3 code

libopencm3 stopped using custom u16/u32 wrappers a while ago.
update contiki submodule revision
Merge remote-tracking branch 'upstream/master'

Conflicts:
	contiki
platform/freertos/contiki-main.c (contiki_main): initialize RF230 only if we have one

This is incredibly ugly but where's little choice than doing it in
contiki_main since Contiki provides no proper API even for such basic
operations, and sneaking the corresponding code into rf230_init or
rf230_warm_reset would not only be difficult but create additional
layering violations.