MAINTAINERS: change IEEE 802.15.4 maintainer

This patch changes the IEEE 802.15.4 subsystem maintainer to Alexander Aring.
We discussed this change before via e-mail and I collected the acks from the
current maintainers.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Acked-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Acked-by: Alexander Smirnov <alex.bluesman.sminov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -4476,8 +4476,7 @@ S:	Supported
 F:	drivers/idle/i7300_idle.c
 
 IEEE 802.15.4 SUBSYSTEM
-M:	Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
-M:	Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
+M:	Alexander Aring <alex.aring@gmail.com>
 L:	linux-zigbee-devel@lists.sourceforge.net (moderated for non-subscribers)
 W:	http://apps.sourceforge.net/trac/linux-zigbee
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/lowpan/lowpan.git