busybox

ifupdown: remove interface from state_list if iface_up fails

Fix the issue where interface is set to the configured state even if
configuration has failed. Add error check to state setting logic.

Signed-off-by: Lauri Hintsala <lauri.hintsala@bluegiga.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>