ar71xx: add support for TP-Link TL-WR1043N v5

ar71xx: add support for TP-Link TL-WR1043N v5

TP-Link TL-WR1043N v5 appears to be identical to the TL-WR1043ND v4,
except that the USB port has been removed and there is no longer a
removable antenna option.

The software is more in line with the Archer series in that it uses a
nested bootloader scheme.

Specifications:

 - QCA9563 at 775 MHz
 - 64 MB RAM
 - 16 MB flash
 - 3 (non-detachable) Antennas / 450 Mbit
 - 1x/4x WAN/LAN Gbps Ethernet (QCA8337)
 - reset and Wi-Fi buttons

Signed-off-by: Tim Thorpe <tim@tfthorpe.net>
Signed-off-by: Ludwig Thomeczek <ledesrc@wxorx.net>