MAINTAINERS: Sort avr32 section alphabetically

The rest of the MAINTAINERS file appears to be sorted
almost-alphabetically, but entries for the newly added AVR32 boards were
added somewhat randomly. This patch sorts the list alphabetically again.

Also update my e-mail address. The old one still works, but it may not
work forever.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>