ar9170: update Makefile, Kconfig and MAINTAINERS

This patch update all necessary Makefile and Kconfig files.

Now you can then enable ar9170 in the kernel configuration under:
Device Drivers --->
	[*] Network device support --->
		Wireless LAN --->
			[*] Wireless LAN (IEEE 802.11)
			<M>   Atheros AR9170 support
			<M>     Atheros AR9170 USB support

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>