firmware: arm_scmi: Parse clock_enable_latency conditionally

The clock_enable_latency field in CLOCK_ATTRIBUTES response message has
been added only since SCMI v3.1. Use the advertised SCMI clock protocol
version as a proper condition check for parsing it, instead of the bare
message length lookup.

Link: https://lore.kernel.org/r/20220330150551.2573938-13-cristian.marussi@arm.com


Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>