iproute: fix unit conversion of rtt/rttvar/rto_min

Since July 2008 (2.6.27, c1e20f7c8b9), the kernel stores the values for
RTAX_{RTT{,VAR},RTO_MIN} in milliseconds. When using a kernel > 2.6.27 with
the current iproute2, conversion of these values is broken in either way.

This patch
 * updates the code to pass and retrieve milliseconds;
 * since values < 1msec would be rounded up, also drops the usec/nsec variants;
 * since there is no way to query kernel HZ, also drops the jiffies variant.

Arguments such as
	rtt		3.23sec
	rto_min		0xff
	rto_min		0.200s
	rttvar		25ms
now all work as expected when reading back previously set values.
diff --git a/lib/utils.c b/lib/utils.c
index 52f2b1f..95adc0c 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -119,28 +119,15 @@
 	}
 	if (p == arg)
 		return -1;
-
-	if (__iproute2_hz_internal == 0)
-                __iproute2_hz_internal = __get_hz();
-	
 	*raw = 1;
 
 	if (*p) {
 		*raw = 0;
                 if (strcasecmp(p, "s") == 0 || strcasecmp(p, "sec")==0 ||
                     strcasecmp(p, "secs")==0)
-                        t *= __iproute2_hz_internal;
+                        t *= 1000;
                 else if (strcasecmp(p, "ms") == 0 || strcasecmp(p, "msec")==0 ||
                          strcasecmp(p, "msecs") == 0)
-                        t *= __iproute2_hz_internal/1000.0;
-                else if (strcasecmp(p, "us") == 0 || strcasecmp(p, "usec")==0 ||
-                         strcasecmp(p, "usecs") == 0)
-                        t *= __iproute2_hz_internal/1000000.0;
-                else if (strcasecmp(p, "ns") == 0 || strcasecmp(p, "nsec")==0 ||
-                         strcasecmp(p, "nsecs") == 0)
-                        t *= __iproute2_hz_internal/1000000000.0;
-		else if (strcasecmp(p, "j") == 0 || strcasecmp(p, "hz") == 0 ||
-			 strcasecmp(p,"jiffies") == 0)
 			t *= 1.0; /* allow suffix, do nothing */
                 else
                         return -1;