lttng: add v4l2 tracing support

changes are merged from this commit;

https://github.com/MentorEmbedded/meta-thales-sophie-lite/commit/
7a43bbe41adcf22249ecfa5831783a0f5da0e677

commit is slightly modified for lttng-2.3.0

Signed-off-by: Fahad Usman <fahad_usman@mentor.com>