The sysupgrade-tar image build is not defined for this target, do not
add a build instruction for it. The build system will use the definition
from the dna_valokuitu-plus-ex400 board and the build will fail.
This fixes the build of the ramips target.
Fixes: 665c2154ef ("ramips: add basic support for tp-link er605-v2")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
746e894877