Support for Raspberry Pi Model B

Combined the work of 
Steve Bate: https://github.com/steve-bate/ChibiOS-RPi
z08840: https://github.com/steve-bate/ChibiOS-RPi/issues/2#issuecomment-43964748
Vergil Cola: http://lightsurge2.blogspot.sg/2014/06/chibiosrt-i2c-on-raspberry-pi-rev-2.html
and made them 2.6.6 compatible