ath79: fix SUPPORTED_DEVICES not matching ar71xx board names

ath79: fix SUPPORTED_DEVICES not matching ar71xx board names

Based on a script for comparison, this fixes (hopefully) all errors
in SUPPORTED_DEVICES for ar71xx->ath79 upgrade.

Devices where old string is removed as the device does not exist
in ar71xx:
- dlink_dir-859-a1
- tplink_archer-a7-v5
- tplink_cpe510-v3 [only in master]

Devices where string is changed because it did not match the board
name in ar71xx:
- tplink_tl-mr3220-v1
- tplink_tl-mr3420-v1
- tplink_tl-wr2543-v1
- tplink_tl-wr741nd-v4
- tplink_tl-wr841-v7
- ubnt_unifiac-mesh
- ubnt_unifiac-mesh-pro
- ubnt_unifiac-pro

For this device, the correct string could not be found, but we could
not determine the correct one. Thus, the string is removed for now:
- tplink_tl-wr740n-v4

The script for checking this is quite simple (note that newer
entries, i.e. ath79->ath79 upgrade, are displayed as missing):

  newpath=target/linux/ath79/image/
  oldpath=target/linux/ar71xx/base-files/lib/ar71xx.sh

  for s in $(grep -roh "SUPPORTED_DEVICES.*" $newpath | sed 's/SUPPORTED_DEVICES *.= *//'); do
    found="Missing"
    grep -q -r "\"$s\"" $oldpath && found="Found"
    echo "$s: $found."
  done

The errors might be filtered by appending 'grep "Missing"' to the script.

Fixes: FS#2751
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
(cherry picked from commit 07ce940b77e6aceb095b0a16dda41e190dfc5b87)