TPLINK_BOARD_NAME has been renamed to TPLINK_BOARD_ID a long time
ago (7d6c63d875: "build: rename TPLINK_BOARD_NAME to
TPLINK_BOARD_ID" for ar71xx), and before introducing ath79 target
at all.
TPLINK_BOARD_NAME seems to have been introduced into ath79 target
only by mistake. It has never been used. Remove it.
Fixes: 53c474abbd ("ath79: add new OF only target for QCA MIPS silicon")
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>