cpufreq: intel_pstate: Use likely() optimization in intel_pstate_sample()

The comment above the condition `if (cpu->last_sample_time)` clearly
indicates that the branch is taken for the vast majority of invocations
after the first sample in a cycle. The first sample is a one-time
initialization case.

Add likely() hint to the condition to improve branch prediction for
this performance-critical path in intel_pstate_sample().

Signed-off-by: Yaxiong Tian <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: Yaxiong Tian

drivers/cpufreq/intel_pstate.c

@@ -2542,7 +2542,7 @@ static inline bool intel_pstate_sample(struct cpudata *cpu, u64 time)
 	 * that sample.time will always be reset before setting the utilization
 	 * update hook and make the caller skip the sample then.
 	 */
-	if (cpu->last_sample_time) {
+	if (likely(cpu->last_sample_time)) {
 		intel_pstate_calc_avg_perf(cpu);
 		return true;
 	}