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>

drivers/firmware/arm_scmi/clock.c

@@ -132,8 +132,8 @@ static int scmi_clock_attributes_get(const struct scmi_protocol_handle *ph,
 		u32 latency = 0;
 		attributes = le32_to_cpu(attr->attributes);
 		strlcpy(clk->name, attr->name, SCMI_MAX_STR_SIZE);
-		/* Is optional field clock_enable_latency provided ? */
-		if (t->rx.len == sizeof(*attr))
+		/* clock_enable_latency field is present only since SCMI v3.1 */
+		if (PROTOCOL_REV_MAJOR(version) >= 0x2)
 			latency = le32_to_cpu(attr->clock_enable_latency);
 		clk->enable_latency = latency ? : U32_MAX;
 	}