Use similiar naming scheme as ath79.
Since the fritz 7360 v2 was only in the tree for 2 days, there
is no compatibility for the old image.
Users which has installed the fritz 7360 v2 before this change, must
use sysupgrade --force to skip checks on the board.
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Reviewed-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
