avr32: update default configurations for ATNGW100, ATSTK1002 and ATSTK1006

This patch updates the default configuration for ATNGW100 (also for the
EVKLCD10X configs), ATSTK1002 and ATSTK1006.

By default all kernels will now have support for EXT2/3/4 out of the box, this
is handy if the user wants to boot from SD-Card.
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>