[MIPS64] Enable mips64 clang

Change-Id: I737f40ff1d4c71c21bea5159d1b0acee89fe32a2
diff --git a/core/clang/TARGET_mips.mk b/core/clang/TARGET_mips.mk
index e70e254..de615b0 100644
--- a/core/clang/TARGET_mips.mk
+++ b/core/clang/TARGET_mips.mk
@@ -43,7 +43,7 @@
   $(CLANG_CONFIG_mips_TARGET_EXTRA_CFLAGS)
 
 $(clang_2nd_arch_prefix)CLANG_TARGET_GLOBAL_CPPFLAGS := \
-  $(call $(clang_2nd_arch_prefix)convert-to-clang-flags,$(clang_2nd_arch_prefix)$(TARGET_GLOBAL_CPPFLAGS)) \
+  $(call $(clang_2nd_arch_prefix)convert-to-clang-flags,$($(clang_2nd_arch_prefix)TARGET_GLOBAL_CPPFLAGS)) \
   $(CLANG_CONFIG_mips_TARGET_EXTRA_CPPFLAGS)
 
 $(clang_2nd_arch_prefix)CLANG_TARGET_GLOBAL_LDFLAGS := \