MAINTAINERS: change AVR32 and AT32AP maintainer

Alter the maintainer of the AVR32 architecture and the AVR32/AT32AP
machine support to me.  Haavard is moving on to new challenges, and we've
found it better to transfer the maintainer part to me.  I will have good
contact with Haavard anyway.

Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>