phc2phc use defaultmaxfreq (facebook#422)

Summary:
Pull Request resolved: facebook#422

WHAT?

Fixes potential issue with pi servo frequency not being set when there is a failure getting it from the device

WHY?
🔨

Considerations:

 - How was this caugh?
   - Found during ts2phc rewrite, this looked funky. ts2phc separates this into function, and upon testing that function this was found.

Reviewed By: abulimov

Differential Revision: D63701624

fbshipit-source-id: 2c1173f67f3d2b02f17252fb9e26b895c042264b

cmd/ptpcheck/cmd/phc2phc.go

@@ -80,9 +80,9 @@ func phc2phcRun(srcDevice string, dstDevice string, interval time.Duration, step
 	if err != nil {
 		log.Warningf("max PHC frequency error: %v", err)
 		maxFreq = phc.DefaultMaxClockFreqPPB
-	} else {
-		pi.SetMaxFreq(maxFreq)
 	}
+	pi.SetMaxFreq(maxFreq)
+
 	log.Debugf("max PHC frequency: %v", maxFreq)
 
 	for ; ; time.Sleep(interval) {