BB10: Video recording is broken because of several mistakes in framerate selection algorithm

After applying patch from QTBUG-43752, it became possible to record the video. However usualy it will fail, because of several problems in video recording initialization code

A quick look at
https://qt.gitorious.org/qt/qtmultimedia/source/2099a8c3c77eea56b95a60e12f265b4eb1d8913d:src/plugins/qnx/camera/bbcamerasession.cpp#L573
shows several problems:

• supportedFrameRates has a memory issue: usually OS will report less (or more?) than 20 supported framerates, so last values in result list will be random
• API documentation doesn't guarantee that returned framerates are sorted, so it is incorrect to just take last element in line 578. In our case the code will take invalid random value returned by supportedFrameRates.
• The code just ignores "calculated" frameRate value not passing it to camera_set_video_property.

Sometimes this code works, sometimes not.