Use DMB ST for store fence.

Change-Id: Ic713f30fcec0f2d2eb486c549917575ff0afa82f
diff --git a/include/cutils/atomic-arm.h b/include/cutils/atomic-arm.h
index 5e27d03..004cc0c 100644
--- a/include/cutils/atomic-arm.h
+++ b/include/cutils/atomic-arm.h
@@ -41,8 +41,7 @@
 }
 extern inline void android_memory_store_barrier(void)
 {
-    /* TODO: use "dmb st" once the toolchain understands it */
-    __asm__ __volatile__ ("dmb" : : : "memory");
+    __asm__ __volatile__ ("dmb st" : : : "memory");
 }
 #elif defined(__ARM_HAVE_LDREX_STREX)
 extern inline void android_memory_barrier(void)