pv3, fix missing $ in math.

rc_shared.sh

@@ -1252,7 +1252,7 @@ function pv3 {
 		return $status
 	fi
 
-	seconds=(( end - start ))
+	seconds=$(( end - start ))
 	h=$(( seconds / 60 / 60 ))
 	m=$(( seconds / 60 % 60 ))
 	s=$(( seconds % 60 ))