dumpvar: Fix Lunch Menu View when Flags are not used

Originally if you lunched a device that didn't have USE_HOST_4_8 or USE_O3_OPTIMIZATIONS set to true you'd see USE_HOST_4_8= (blank).  This should make sure it will print false if not being used to counter balance the true you see if enabled.

Signed-off-by: Chet Kener <Cl3Kener@gmail.com>