Always set list_for_each_entry iterator to NULL

src/allsta.c

src/cntlr.c

src/cntlr_cmdu.c

src/cntlr_commands_impl.c

src/cntlr_tlv.c

src/cntlr_tlv_qos.c

src/cntlr_ubus_dbg.c

src/config.c

src/dpp.c

src/plugins/steer/rcpi/rcpi.c