firmware: arm_scmi: Add support to reset the debug metrics

It is sometimes useful to reset all these SCMI communication debug
metrics especially when we are interested in analysing these metrics
during a particular workload or for a fixed time duration. Let us
add the capability to reset all these metrics as once so that they
can be counted during the period of interest.

Signed-off-by: Luke Parkin <luke.parkin@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Message-Id: <20240805131013.587016-6-sudeep.holla@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>