avr32: Add MIMC200 board support

Please consider the following patch which adds support for a new AVR32
based board.

The board is closely based on Atmel's NGW100 reference board, but has an
extra 8MByte FLASH and 128KByte FRAM.

Signed-off-by: Mark Jackson <mpfj@mimc.co.uk>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>