Revert "Settings: Fix possible illegal argument exception"

This reverts commit 3fa54a0405d1d0f9d30124b459975e655dca298d.
Revert "Settings: Don't crash if we pause too quickly"

This reverts commit 8a595285cea8ac8598983abbb6a4a78ca293e133.
Settings: Fix possible illegal argument exception

User reported this exception during toggle settings from QS
Just check if receiver where attached before unregister them.

Change-Id: I184042bd05af28dc2ad2272fba25b650ccd2c8c1