avr32: add grasshopper (ICnova AP7000) board

The grasshopper board is a neat avr32 evaluation kit produced by In-Circuit
GmbH.
See http://www.ic-board.de/product_info.php?info=p75_ICnova-AP7000-Base.html


for detailed information about this device.

Signed-off-by: Andreas Bießmann <biessmann@corscience.de>
Signed-off-by: Reinhard Meyer <u-boot@emk-elektronik.de>