pfsync tests: check for the correct IP address

When checking if the state synced over we should look for
198.51.100.254, not 198.51.100.2. The test worked because the incorrect
address is a substring of the correct one, but we should fix it anyway.

Reported by:	Naman Sood <naman@freebsdfoundation.org>
MFC after:	1 week

tests/sys/netpfil/pf/pfsync.sh

@@ -87,7 +87,7 @@ common_body()
 	sleep 2
 
 	if ! jexec two pfctl -s states | grep icmp | grep 198.51.100.1 | \
-	    grep 198.51.100.2 ; then
+	    grep 198.51.100.254 ; then
 		atf_fail "state not found on synced host"
 	fi
 }