mem: fix printing of 1st cache tags line

Rather than having the 1st line on the Log line and every other line on its
own, add a new line to have a common format for all of them.  Makes parsing
a lot easier.

Reviewed at http://reviews.gem5.org/r/3808/

Signed-off-by: Jason Lowe-Power <jason@lowepower.com>

src/mem/cache/cache.cc

@@ -585,7 +585,7 @@ Cache::promoteWholeLineWrites(PacketPtr pkt)
 bool
 Cache::recvTimingReq(PacketPtr pkt)
 {
-    DPRINTF(CacheTags, "%s tags: %s\n", __func__, tags->print());
+    DPRINTF(CacheTags, "%s tags:\n%s\n", __func__, tags->print());
 
     assert(pkt->isRequest());