include: trace: Add new scmi_xfer_response_wait event

Having a new step to trace SCMI stack while it waits for synchronous
responses is useful to analyze system performance when changing waiting
mode between polling and interrupt completion.

Link: https://lore.kernel.org/r/20211129191156.29322-5-cristian.marussi@arm.com


Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>