[Tizen] Prevent segmentation faults in bluetooth

Fixes are connected with cases when null pointers were not
handled properly. Some other nits fixed.

Change-Id: I4263b2643c2fbd67d8cbe9315235bbec2cb638dd
Merge pull request #428 from piotrowskim/rm_nits_bluetooth

[Tizen] Prevent segmentation faults in bluetooth