Added conditions of logical disk for compute and controller 
Added conditions of logical disk for compute and controller 

define_single_raid_10_logical_disk() returns three values : empty dict, None  and  dictionary with key:value pair. so add condition to handle all the three condition.
- define_single_raid_10_logical_disk() is None -> return None
- define_single_raid_10_logical_disk()  is empty dict() -> return list()
- define_single_raid_10_logical_disk()  is dict()(with key-value pairs) - > return list()(with items)
dsp-jetpack/JetPack,dsp-jetpack/JetPack