[media] v4l2-dev: use event class to deduplicate v4l2 trace events

Trace events with exactly the same parameters and trace output, such as
v4l2_qbuf and v4l2_dqbuf, are supposed to use the DECLARE_EVENT_CLASS and
DEFINE_EVENT macros instead of duplicated TRACE_EVENT macro calls.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>