ath79: re-enable build of TP-Link RE355 v1, RE450 v1 and RE450 v2

ath79: re-enable build of TP-Link RE355 v1, RE450 v1 and RE450 v2

With previous patches these devices have only 128 KiB less space than
RE450 v3. It may be even possible to revert commit 65b6f1c1b251 ("ath79:
move TP-Link RE450 v1 & v2 and RE355 v1 to tiny target") but that was
not done as the device has only 8 MiB flash and will eventually run out of
it anyway.

Signed-off-by: Radek Dostál <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20709
Signed-off-by: Hauke Mehrtens <[email protected]>