ifconfig: Reuse media state in ifmedia_getstate

This restores behavior lost in code cleanup, fixing a regression after
2803fa471e where changing media options
only applies some of the changes, not all.

Reported by:	np
Reviewed by:	donner
MFC after:	immediately
Differential Revision:	https://reviews.freebsd.org/D29741

sbin/ifconfig/ifmedia.c

@@ -159,7 +159,10 @@ media_status(int s)
 struct ifmediareq *
 ifmedia_getstate(void)
 {
-	static struct ifmediareq *ifmr;
+	static struct ifmediareq *ifmr = NULL;
+
+	if (ifmr != NULL)
+		return (ifmr);
 
 	if (ifconfig_media_get_mediareq(lifh, name, &ifmr) == -1)
 		errc(1, ifconfig_err_errno(lifh),