attestation: Rename "chromeos" -> "brillo" in include paths and namespaces

libchromeos is transitioning to libbrillo and chromeos namespaces
and include directory is changing to brillo.

Bug: 24872993
TEST=built for aosp and brillo, all unit tests pass on dragonboard

Change-Id: I3d7f1eb480f9e211606d7ee0a990c4a1bec27ea8
diff --git a/server/main.cc b/server/main.cc
index 247485d..3b001f4 100644
--- a/server/main.cc
+++ b/server/main.cc
@@ -30,7 +30,7 @@
 #include "attestation/server/attestation_service.h"
 #include "attestation/server/dbus_service.h"
 
-#include <brillo/libminijail.h>
+#include <chromeos/libminijail.h>
 
 namespace {