Add support for QAC AR816x/AR817x Gigabit/Fast Ethernet controllers.
These controllers seem to have the same feature of AR813x/AR815x and
improved RSS support(4 TX queues and 8 RX queues).  alc(4) supports
all hardware features except RSS.  I didn't implement RX checksum
offloading for AR816x/AR817x just because I couldn't get
confirmation from the Vendor whether AR816x/AR817x corrected its
predecessor's RX checksum offloading bug on fragmented packets.
This change adds supports for the following controllers.
 o AR8161 PCIe Gigabit Ethernet controller
 o AR8162 PCIe Fast Ethernet controller
 o AR8171 PCIe Gigabit Ethernet controller
 o AR8172 PCIe Fast Ethernet controller
 o Killer E2200 Gigabit Ethernet controller

Tested by:	Many
Relnotes:	yes
MFC after:	2 weeks
HW donated by:	Qualcomm Atheros Communications, Inc.
Document newly added controller AR816x/AR817x.
Oops, fix typo made in r272729.