[CMFileManager] Fix can't copy after disconnect with pc.

[CMFileManager] Fix can't copy after disconnect with pc.

Preconditions
1.insert a sdcard.
2.the phone connect with pc and the usb computer connection as Mount Sd card.

Procedures
1.Go to “File Manager”.
2.Copy a file in sdcard.
3.Connect to pc when the system is copying.
4.The CMFileManager will forced termination and  switch off the connecting with pc.
5.Go to CMFileManager and copy a file in Sd card.

The copy function is invalid and popup "The operation's command was not found ..."

Change-Id: I042550ce69f4c31a6fe46dfc9aeb53b34588d53f