[MIPS64] Enable mips64 clang

(cherry picked from commit 41ca4446370ba90e472e45a8897868855185a6c7)

Change-Id: I0b141c58c88fe86e3a59844f53acc9a0e0a5271c
diff --git a/core/clang/TARGET_mips.mk b/core/clang/TARGET_mips.mk
index 6f4c197..0107519 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 := \