ath79: add support for TP-Link TL-WR941HP v1

ath79: add support for TP-Link TL-WR941HP v1

Specifications:
    SOC:        Qualcomm Atheros TP9343 (750 MHz)
    Flash:      8 Mb (GigaDevice GD25Q64CSIG)
    RAM:        64 Mb (Zentel A3R12E40DBF-8E)
    Serial:     yes, 4-pin header
    Wlan:       Qualcomm Atheros TP9343, antenna: MIM0 3x3:3 RP-SMA
                3 x 2.4GHz power amp module Skyworks (SiGe) SE2576L
    Ethernet:   Qualcomm Atheros TP9343
    Lan speed:  100M ports: 4
    Lan speed:  100M ports: 1
    Other info: same case, ram and flash that TP-Link TL-WR841HP,
                different SOC

    https://forum.openwrt.org/t/adding-device-support-tp-link-wr941hp/

Label MAC addresses based on vendor firmware:
    LAN   *:ee  label
    WAN   *:ef  label +1
    WLAN  *:ee  label

    The label MAC address found in "config" partition at 0x8

Flash instruction:
    Upload the generated factory firmware on web interface.

Signed-off-by: Diogenes Rengo <rengocbx250@gmail.com>
[remove various whitespace issues, squash commits, use short 0x0]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>