Like other architectures, CONFIG_AVR32 can be defined
in arch/avr32/config.mk rather than board header files.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Andreas Bießmann <andreas.devel@googlemail.com>
Acked-by: Andreas Bießmann <andreas.devel@googlemail.com>