common: changed if-else blocks to conform with golint (#16656)

common/bytes.go

@@ -87,15 +87,13 @@ func Hex2BytesFixed(str string, flen int) []byte {
 	h, _ := hex.DecodeString(str)
 	if len(h) == flen {
 		return h
-	} else {
+	}
 	if len(h) > flen {
 		return h[len(h)-flen:]
-		} else {
+	}
 	hh := make([]byte, flen)
 	copy(hh[flen-len(h):flen], h[:])
 	return hh
-		}
-	}
 }
 
 func RightPadBytes(slice []byte, l int) []byte {