ipq806x: add support for IgniteNet SunSpot AC Wave2

ipq806x: add support for IgniteNet SunSpot AC Wave2

The IgniteNet SS-W2-AC2600 is an 802.11ac outdoor (IP-55) access point.
FCC ID: HEDSSW2AC2600

Specification:
 - Qualcomm dual-core IPQ8068 @ 1.4 GHz
 - 256 MB of DDR3L RAM (2x Winbond W631GU6KB-12)
 - 16 MB of SPI NOR (Winbond W25Q128FW)
 - 128 MB of NAND (Macronix MX30UF1G18AC)
 - Qualcomm QCA9994 2.4GHz 802.11bgn
 - Qualcomm QCA9994 5GHz 802.11ac
 - 2 x 10/100/1000 Mbit/s Ethernet
 - 115200, 8N1 RS-232 console (unpopulated RJ-45)
 - Reset button
 - Power and WLAN LEDs
 - Powered via 802.3at PoE or 12V 2A barrel connector

Tested-by: Elektra Wagenrad <onelektra@gmx.net>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>