UPSTREAM: interconnect: Add basic tracepoints

The tracepoints can help with understanding the system behavior of a
given interconnect path when the consumer drivers change their bandwidth
demands. This might be interesting when we want to monitor the requested
interconnect bandwidth for each client driver. The paths may share the
same nodes and this will help to understand "who and when is requesting
what". All this is useful for subsystem drivers developers and may also
provide hints when optimizing the power and performance profile of the
system.

Bug: 151255205
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
(cherry picked from commit c46ab9db64979b0875fff79e1b00013343ca8286)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ia2276cc83a2a73c66207bdf14b87402b96d623a7