nmeter %[mf] behave as %[mt]

[S. Couture & K. Musgrove]

I don't actually use it nor really agree with the way the free memory is 
calculated but current behavior is wrong.

--- busybox-1.9.1/procps/nmeter.c       2008-02-12 11:03:12.000000000 -0500
+++ busybox-1.9.1_nmeter/procps/nmeter.c        2008-02-28 
21:44:35.000251000 -0500
@@ -622,7 +622,7 @@
                put_question_marks(4);
                return;
        }
-       if (s->opt == 'f') {
+       if (s->opt == 't') {
                scale(m_total << 10);
                return;
        }