Devices might be removed and inserted at anytime, so let's ensure we
always do these kind of operations with a good known state of the
HashMap.
The VirtIO code was modified to create devices outside the IRQ handler,
so now it works with the new locking of the devices singleton, but a
better approach might be needed later on.
These methods are no longer needed because SystemServer is able to
populate the DevFS on its own.
Device absolute_path no longer assume a path to the /dev location,
because it really should not assume any path to a Device node.
Because StorageManagement still needs to know the storage name, we
declare a virtual method only for StorageDevices to override, but this
technique should really be removed later on.
