Bug 1045461: Fix HFP fallback code to work with latest Bluetooth changes, r=shuang

Recent patches to Bluetooth introduced asynchronous initialization of
profile manager. The code in hfp-fallback was not adapted then. This
patch updates the broken code.
Bug 1045461: Fix HFP fallback code to work with latest Bluetooth changes (under bluetooth2/), r=btian

Recent patches to Bluetooth introduced asynchronous initialization of
profile manager. The code in hfp-fallback was not adapted then. This
patch updates the broken code.