Mark kQuickReadBarrierForRootSlow as direct entry point on MIPS.

Change-Id: I35caa32c9773646692706642188ab522237a68ac
diff --git a/runtime/arch/mips/entrypoints_direct_mips.h b/runtime/arch/mips/entrypoints_direct_mips.h
index f9c5315..74e7638 100644
--- a/runtime/arch/mips/entrypoints_direct_mips.h
+++ b/runtime/arch/mips/entrypoints_direct_mips.h
@@ -45,7 +45,8 @@
       entrypoint == kQuickCmpgFloat ||
       entrypoint == kQuickCmplDouble ||
       entrypoint == kQuickCmplFloat ||
-      entrypoint == kQuickReadBarrierSlow;
+      entrypoint == kQuickReadBarrierSlow ||
+      entrypoint == kQuickReadBarrierForRootSlow;
 }
 
 }  // namespace art