alpha: remove redundant err variable

Return value from __hw_perf_event_init() directly instead
of taking this in another redundant variable.

Reported-by: Zeal Robot <[e-mail]>
Signed-off-by: Minghao Chi <[e-mail]>
Signed-off-by: CGEL ZTE <[e-mail]>
Signed-off-by: Matt Turner <[e-mail]>

arch/alpha/kernel/perf_event.c

···
  */
 static int alpha_pmu_event_init(struct perf_event *event)
 {
-	int err;
-
 	/* does not support taken branch sampling */
 	if (has_branch_stack(event))
 		return -EOPNOTSUPP;
···
 		return -ENODEV;
 
 	/* Do the real initialisation work. */
-	err = __hw_perf_event_init(event);
-
-	return err;
+	return __hw_perf_event_init(event);
 }
 
 /*