tools/lib/atben.c (atben_interrupt_wait): don't time out if timeout_ms == 0
tools/lib/atben.c (atben_interrupt_wait): don't time out if timeout_ms == 0

cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan