mem-cache: Use secure flag in FALRU's findBlock

FALRU's findBlock() must use the secure flag to assure proper
functionality.

Change-Id: I54e9fbd3c9093b3e8043c4c6c850b74a8f1f5ec0
Reviewed-on: https://gem5-review.googlesource.com/10081
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

src/mem/cache/tags/fa_lru.cc

@@ -179,6 +179,7 @@ FALRU::findBlock(Addr addr, bool is_secure) const
 
     if (blk && blk->isValid()) {
         assert(blk->tag == blkAddr);
+        assert(blk->isSecure() == is_secure);
     } else {
         blk = nullptr;
     }