Fatal error while playing certain mkv files.

In addTracks() function, the value of codecPrivateSize is zero
for the certain mkv contents, which causes this fatal error.
With this fix, error is returned whenever the value of
codecPrivateSize is less than 2, to avoid the fatal error.

Change-Id: I2f464deb7444d4c129aaa4d77bba35a3835bf7e1
Signed-off-by: gbhakteX <gurudattax.bhakte@intel.com>
Signed-off-by: Mazhar <mazharx.sameullah@intel.com>